Imprint lithography

ABSTRACT

An imprint lithography apparatus having a first frame to be mounted on a floor, a second frame mounted on the first frame via a kinematic coupling, an alignment sensor mounted on the second frame, to align an imprint lithography template arrangement with a target portion of a substrate, and a position sensor to measure a position of the imprint lithography template arrangement and/or a substrate stage relative to the second frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/812,844, filed Jan. 28, 2013, now allowed, which is the U.S. nationalphase entry of PCT Patent Application No. PCT/EP2011/059831, filed Jun.14, 2011, which claims the benefit of priority of U.S. provisionalapplication 61/370,940, which was filed on Aug. 5, 2010 and which isincorporated herein in its entirety by reference. And also claims thebenefit of priority of U.S. provisional application 61/382,151, whichwas filed on Sep. 13, 2010 and which is incorporated herein in itsentirety by reference. And also claims the benefit of priority of U.S.provisional application 61/418,214, which was filed on Nov. 30, 2010 andwhich is incorporated herein in its entirety by reference. And alsoclaims the benefit of priority of U.S. provisional application61/426,275, which was filed on Dec. 22, 2010 and which is incorporatedherein in its entirety by reference.

FIELD

The present invention relates to imprint lithography, and in particularto an imprint lithography apparatus (or related apparatus) and/or animprint lithography method or process (or related method or process).

BACKGROUND

In lithography, there is an ongoing desire to reduce the size offeatures in a lithographic pattern in order to increase the density offeatures on a given substrate area. In photolithography, the push forsmaller features has resulted in the development of technologies such asimmersion lithography and extreme ultraviolet (EUV) lithography, whichare, however, rather costly.

A potentially less costly road to smaller features that has gainedincreasing interest is so-called imprint lithography, which generallyinvolves the use of a “stamp” (often referred to as an imprint templateor an imprint lithography template) to transfer a pattern onto asubstrate. An advantage of imprint lithography is that the resolution ofthe features is not limited by, for example, the emission wavelength ofa radiation source or the numerical aperture of a projection system.Instead, the resolution is mainly limited to the pattern density on theimprint lithography template, and the dimensions of pattern featuresconstituting that pattern.

Imprint lithography involves the patterning of an imprintable medium ona surface of a substrate to be patterned. The patterning may involvebringing together a patterned surface of an imprint lithography templateand a layer of imprintable medium (e.g., moving the imprint lithographytemplate toward the imprintable medium, or moving the imprintable mediumtoward the imprint lithography template, or both) such that theimprintable medium flows around and about protrusions on, or recessedin, the patterned surface, to adopt the topography of that patternedsurface. The protrusions define pattern features of the patternedsurface of the imprint template. Typically, the imprintable medium isflowable when the patterned surface and the imprintable medium arebrought together. Following patterning of the imprintable medium, theimprintable medium is suitably brought into a non-flowable or frozenstate (i.e. a fixed state), for example by illuminating the imprintablemedium with actinic radiation such as UV radiation. The patternedsurface of the imprint lithography template and the patternedimprintable medium are then separated. The substrate and patternedimprintable medium are then typically processed further in order topattern or further pattern the substrate. The imprintable medium may beprovided in the form of droplets (e.g. deposited by ink jet printing) onthe surface of a substrate to be patterned, but may alternatively beprovided using spin coating or the like.

As with any form of lithography, it is desirable to be able to applypatterns to a substrate in an accurate and consistent manner. In someinstances, it may be required to align the application of a pattern ontop of and relative to a previously applied (and/or processed) pattern.This is known as an overlay requirement. It becomes increasinglydifficult to meet these pattern application requirements and/or overlayrequirements if there are positional errors of, or in the measurementof, the imprint lithography template with respect to a target portion(which includes an area, region, or the like) of a substrate.

SUMMARY

An imprint lithography apparatus may be prone to the above-mentionedpositional errors. Accordingly, it is desirable, for example, to providean imprint lithography apparatus which reduces the magnitude and/orfrequency of such positional errors. State of the art imprintlithography apparatuses and/or methods may have one or more problems ordisadvantages associated with or related to one or more of: resolution,overlay, productivity, focus, cost of goods, cost of hardware,throughput, defectivity, amongst other issues. It is desirable, forexample, to provide an imprint lithography related apparatus and/ormethod which obviates or mitigates one or more problems or disadvantagesof the art, whether identified herein or elsewhere, and/or whichprovides an alternative to state of the art lithography apparatusesand/or methods.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: a first frame to be mounted on a floor; a secondframe mounted on the first frame via a kinematic coupling; an alignmentsensor mounted on the second frame, for aligning an imprint lithographytemplate arrangement with a target portion of a substrate; and one ormore position sensors for measuring a position of the imprintlithography template arrangement and/or a substrate stage relative tothe second frame.

The first frame may be mounted on the floor by one or more vibrationisolation systems.

A portion of the second frame may extend from outside of the firstframe, and into a region located within the first frame, so that themeasurement of position may be undertaken relative to or using thatportion of the second frame.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: a first frame to be mounted on a floor; a secondframe mounted on the first frame via a vibration isolation system; animprint lithography template arrangement configured, at least in use, tobe mounted on the second frame via a kinematic coupling; and analignment sensor mounted on the second frame, for aligning the imprintlithography template arrangement with a target portion of a substrate;and one or more position sensors for measuring a position of a substratestage relative to the second frame.

The second frame may be located substantially within the first frame.

The apparatus may further comprise one or more release compensationactuators connected between the first frame and the imprint lithographytemplate arrangement.

A point or points of connection of the one or more release compensationactuators may be linked (e.g. by proximity or other spatialrelationship) to a point of connection of the kinematic coupling viawhich the imprint lithography template arrangement is mounted to thesecond frame.

The point or points of connection of the one or more releasecompensation actuators may be on an opposite side of the imprintlithography template arrangement to the point of connection of thekinematic coupling via which the imprint lithography templatearrangement is mounted to the second frame.

The one or more release compensation actuators may extend through thesecond frame.

According to either the first or second aspects of the invention, thefollowing features may be used in addition to, or as an alternative to,those features already described above:

The substrate stage may be a five degree of freedom short strokesubstrate stage (which includes six degrees of freedom or greater). Thesubstrate stage may be a five degree of freedom (which includes sixdegrees of freedom or greater) isolated (e.g. spatially isolated orseparated) short stroke substrate stage. The substrate stage mayadditionally comprise or be a three degree of freedom long strokesubstrate stage.

The substrate stage may be capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes), andalong an axis perpendicular to that plane (z axis).

The substrate stage may be capable of rotational movement about the twoaxes that are parallel to the plane of the substrate (rotation about xand y axes).

The substrate stage may be capable of rotational movement about the twoaxes that are parallel to the plane of the substrate (rotation about xand y axes), and about the axis that is perpendicular to that plane(rotation about z axis), and the substrate stage may be capable oftranslational short stroke movement along the two axes parallel to theplane of the substrate (x and y axes).

The imprint lithography template arrangement may be capable oftranslational short stroke movement along the two axes parallel to theplane of the substrate (x and y axes), and the imprint lithographytemplate arrangement may be capable of rotational movement about theaxis that is perpendicular to that plane (rotation about z axis).

The substrate stage may be capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes).

The substrate stage may be capable of rotational movement about the twoaxes that are parallel to the plane of the substrate (rotation about xand y axes).

The substrate stage may be capable of rotational movement about the twoaxes that are parallel to the plane of the substrate (rotation about xand y axes), and about the axis that is perpendicular to that plane(rotation about z axis), and the substrate stage may be capable oftranslational short stroke movement along the two axes parallel to theplane of the substrate (x and y axes).

The imprint lithography template arrangement may be capable of longstroke movement along an axis perpendicular to the plane of thesubstrate (z axis).

The imprint lithography template arrangement may be capable oftranslational short stroke movement along the two axes parallel to theplane of the substrate (x and y axes), and the imprint lithographytemplate arrangement may be capable of rotational movement about theaxis that is perpendicular to that plane (rotation about z axis).

An object referred to herein as being capable of movement or rotationwill be understood to encompass both movement or rotation of the objectmy some inherent driving means, and movement or rotation by a separate(e.g. independent) driving means.

The apparatus may further comprise one or more heat shields forshielding the second frame.

The second frame may be formed from a material with a low coefficient ofthermal expansion, for example less than or substantially equal to 1μm/m·K and/or a high thermal conductance, for example greater than 20W/(m·K). The apparatus alternatively or additionally comprise a coolingor thermal conditioning system to cool or thermally condition the secondframe. The second frame may preferably be formed from aluminium.

The second frame may be constructed and/or arranged to have internaldynamical modes that are of a high frequency (e.g. typically 100 Hz orhigher).

The substrate stage may be coupled to the first frame, for example bybeing in direct or indirect connection (e.g. via an intermediatestructure) with the first frame.

The substrate stage may be, or may comprise, or may form a part of oneor more of: a substrate holder; a positioner of the substrate; apositioner of a substrate holder.

The first frame may be, or may be referred to as a base frame, and/orwherein the second frame may be, or may be referred to as a metrologyframe.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: a base frame; a metrology frame; an imprintlithography template arrangement in connection with the base frame orthe metrology frame via one or more kinematic couplings and one or morerelease compensation actuators.

One or more kinematic couplings may be located in series with the one ormore release compensation actuators.

A point or points of connection of the one or more release compensationactuators may be on an opposite side of the imprint lithography templatearrangement to a point or points of connection of the kinematiccouplings.

According to an aspect, there is provided an imprint lithography methodfor using an imprint lithography apparatus, the apparatus comprising: abase frame; a metrology frame; and an imprint lithography templatearrangement; and the method comprising: using the imprint lithographyarrangement to imprint a pattern into a layer of imprintable mediumprovided on a substrate, when the imprint lithography arrangement is inconnection with the metrology frame; fixing the pattern provided in theimprintable medium; moving the imprint lithography template arrangementto disconnect the imprint lithography arrangement from the metrologyframe, and connecting the imprint lithography template arrangement tothe base frame; and releasing the imprint lithography templatearrangement from the substrate.

The imprint lithography template arrangement may be moved by movement ofa substrate stage that holds the substrate.

Movement of the substrate will cause movement of the imprint lithographytemplate arrangement, because the fixing of the pattern will cause theimprint lithography template arrangement to be at least partiallyattached to the substrate, via the fixed pattern. Movement may be towardthe imprint lithography template arrangement, which may make it easierto move the imprint lithography template arrangement (e.g. moving thesubstrate away from the imprint lithography template arrangement mayresult in the substrate at least partially releasing from the imprintlithography template arrangement, which may be undesirable, at least atthis stage of the method).

Releasing the imprint lithography template arrangement may compriseholding the imprint lithography template arrangement using an actuatorin connection with the base frame, and pulling the substrate away fromthe imprint lithography template arrangement via movement of thesubstrate stage that holds the substrate.

The imprint lithography template arrangement may be biased toward (e.g.into) connection with the metrology frame. The aforementioned movementof the imprint lithography template arrangement may at least partiallyovercome the bias.

The actuator may be (additionally) capable of biasing the imprintlithography template arrangement toward (e.g. into) connection with themetrology frame.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: a base frame; a metrology frame connected to thebase frame; and an imprint lithography template arrangement; the imprintlithography template arrangement being movable between a firstconfiguration and a second configuration, the first configuration beingdefined by the imprint lithography template arrangement being connectedto the metrology frame, and the second configuration being defined bythe imprint lithography template arrangement being disconnected from themetrology frame and connected to the base frame.

According to an aspect, there is provided an imprint lithographytemplate arrangement (e.g. an imprint lithography template) clampingconfiguration, the clamping configuration including at least one clampthat comprises: a base region; a burl extending from the base region,and arranged in use to come into contact with the imprint lithographytemplate arrangement; a space that surrounds the burl; one or more sealwalls extending from the base region and surrounding the space thatsurrounds the burl, the burl extending further from the base region thanthe one or more seal walls; the one or more seal walls being configuredto provide, in use, an at least a partial seal with the imprintlithography template arrangement, when the space is at a lower pressurethan ambient pressure; and wherein the burl is at least partiallyflexible in a direction parallel to a plane of the imprint lithographytemplate arrangement (i.e. perpendicular or orthogonal to the length ofthe burl), to allow for movement, expansion or compression of theimprint lithography template arrangement, without slip of the burlrelative to the imprint lithography template arrangement.

The burl may be: at least 1 mm long; at least 5 mm long; at least 5-10mm; at least 10 mm long; and/or less than 100 mm long. Such a length ofburl may ensure that the burl is sufficiently flexible in a directionperpendicular or orthogonal to its length.

The burl may extend: 1-10 μm further from the base region than the oneor more seal walls; or 3-5 μm further from the base region than the oneor more seal walls. This may provide a gap of similar size between theseal walls and the imprint lithography template arrangement sufficientfor a seal to be established or maintained, while at the same timepreventing contact of the walls with the imprint lithography templatearrangement, which might otherwise generate contamination, frictionand/or distortion.

The clamp may comprise a plurality of burls, constructed and arranged tobe distributable (i.e. in use) around a periphery of the imprintlithography template arrangement.

The one or more seal walls may comprise: an outer seal wall that extendsaround an outer perimeter of a region containing the burl or burls; andan inner seal wall that extends around an inner perimeter of the regioncontaining the burl or burls.

The clamping configuration may comprise a plurality of the describedclamps, constructed and arranged so as to be disposable (i.e. in use)around a periphery of the imprint lithography template arrangement.

The clamp or clamping configuration may be, or may form a part of,another imprint lithography template arrangement (e.g. an imprintlithography template holder).

According to an aspect, there is provided a method of releasing animprint lithography template from a substrate that is held on asubstrate stage, the method comprising: pulling the substrate and theimprint lithography template away from one another (which could involvemoving one or both of the substrate and the imprint lithographytemplate, for example by movement of respective holding stages, orholders); and applying a rotation moment to one or both of the imprintlithography template and substrate toward the other of the imprintlithography template and substrate, such that at a radial extremity ofan interface between the imprint lithography template and the substrate,there is a cumulative force acting on the substrate that results in thesubstrate being held on the substrate stage. This may be described asthe rotation being such that there is pressing force into the substrateat the radial extremity.

The pulling and applying of the rotation moment (i.e. the rotating) maybe undertaken at the same time. The pulling and rotating may beundertaken using the same apparatus. The pulling and rotating may beundertaken in the same process. The pulling may result in the rotation.The rotation may result in the pulling.

A relationship between a pulling force, or a component thereof, actingthrough a center of the imprint lithography template, and a momentassociated with the rotation is defined as: F<M/b, where F is thepulling force, or the component thereof, acting through the center ofthe imprint lithography template, M is the moment induced by therotation, and b is a radial distance from the center of the imprintlithography template to the radial extremity of the interface betweenthe imprint lithography template and the substrate.

The method may be undertaken at a peripheral region of the substrate,where holding forces provided by a substrate stage might be lower thanat, for example, a more central region of the substrate.

According to an aspect, there is provided an imprint lithographyapparatus comprising: an imprint lithography template holder for holdingan imprint lithography template; a substrate stage for holding asubstrate; wherein, during release of an imprint lithography templatefrom a substrate, one or both of the imprint lithography template holderand substrate stage are constructed and arranged to be movable to: pullthe substrate and the imprint lithography template away from oneanother; and apply a rotation moment to one or both of the imprintlithography template and substrate toward the other of the imprintlithography template and substrate, such that at a radial extremity ofan interface between the imprint lithography template and the substrate,there is a cumulative force acting on the substrate that results in thesubstrate being held on the substrate stage.

According to an aspect, there is provided an actuation arrangement forpositioning and/or deforming an imprint lithography templatearrangement, the arrangement comprising: a first actuator, locatable, inuse, on a first side of the imprint lithography template arrangement; asecond actuator, locatable, in use, on a second, opposite side of theimprint lithography template arrangement; and a signal amplifier foramplifying a control signal applicable to both the first actuator andthe second actuator.

The first actuator may be locatable directly opposite the secondactuator.

The actuation arrangement may comprise: a plurality of first actuators,locatable, in use, on a first side of the imprint lithography templatearrangement; a plurality of second actuators, locatable, in use, on asecond, opposite side of the imprint lithography template arrangement;and a signal amplifier for amplifying a control signal applicable todirectly opposing actuators of the pluralities, or for amplifying acontrol signal applicable to groups of actuators locatable on oppositesides of the imprint lithography template arrangement.

Each actuator may be a piezoelectric actuator or a Lorentz actuator.

The actuation arrangement may form part of an imprint lithographytemplate holder (or, more generally, an imprint lithography templatearrangement), which includes the actuation arrangement being an imprintlithography template holder (or, more generally, an imprint lithographytemplate arrangement).

The term ‘locatable’ used to describe the position of actuators mayinclude ‘located’. For example, in some embodiments, an imprintlithography template arrangement (e.g. an imprint lithography templateholder) may be or comprise the actuation arrangement, and this imprintlithography template arrangement may be in permanent, or long-term,connection with the imprint lithography template. The actuators willthen be located on one or more sides of the imprint lithographytemplate.

According to an aspect, there is provided an imprint lithography method,comprising: imprinting an imprint lithography template into a layer ofimprintable medium provided on a substrate to form a pattern in thatlayer of imprintable medium; controlling a position (which includesorientation) or deformation of the imprint lithography template relativeto the substrate (e.g. a target portion thereof) when the imprintlithography template is imprinted into the imprintable medium; andfixing the pattern provided in the layer of imprintable medium; whereincontrolling the position or deformation of the imprint lithographytemplate relative to the substrate comprises: i) undertaking relativelyhigh bandwidth control at a first level when the imprintable medium isin an unfixed, substantially liquid and/or flowable state; then/followedby ii) undertaking higher bandwidth control at a second level, higherthan the first level, when the imprintable medium is in an intermediatestate, in-between the unfixed, substantially liquid and/or flowablestate, and a fixed, substantially solid state; then/followed by iii)relatively low bandwidth control when the imprintable medium is in afixed, substantially solid state.

A transition between the higher bandwidth control at the second leveland the relatively low bandwidth control will occur when the imprintablemedium is in an intermediate state.

A transition between the higher and higher bandwidth control may alsooccur when the imprintable medium is in an intermediate state.

Controlling a position or deformation of the imprint lithographytemplate relative to the substrate may comprise control of one or moreservomechanisms.

Controlling a position of the imprint lithography template relative tothe substrate when the imprint lithography template is imprinted intothe imprintable medium may comprise aligning, or maintaining alignmentof, the imprint lithography template arrangement relative to a targetportion the substrate.

Controlling a position or deformation of the imprint lithographytemplate relative to the substrate may comprise controlling a positionor deformation of the imprint lithography template, or the substrate, orboth (in series or parallel) the imprint lithography template relativeand the substrate.

According to an aspect, there is provided an actuation arrangement forpositioning and/or deforming an imprint lithography templatearrangement, the arrangement comprising: one or more actuators,locatable, in use, around the imprint lithography template arrangement;fixed abutment points for fixing three degrees of freedom of the imprintlithography template arrangement, the three degrees of freedom being:translation along a first axis parallel to a plane of the imprintlithography template arrangement; translation along a second axis,perpendicular to the first axis and parallel to the plane of the imprintlithography template arrangement; and rotation about a third axis,perpendicular to the first and second axes; the actuation arrangementfurther comprising: a controller for controlling a force provided by theone or more actuators to the imprint lithography template arrangement,the controller being configured to ensure that the provided force issuch that a cumulative force acting along the first axis, second axis,and about the third axis, is minimal.

The actuation arrangement may further comprise a biasing member,arranged to bias, in use, the imprint lithography template arrangementinto contact with the fixed abutment points (i.e. to fix, or facilitatethe fixing of, the three degrees of freedom discussed above).

The aforementioned cumulative force may be described as minimal in thatthat a force applied to one, more or all fixed abutment points (or alongor about the aforementioned axes), is: less than 5% of a total forceapplied to the imprint lithography template arrangement; or less than 4%of a total force applied to the imprint lithography templatearrangement; or less than 3% of a total force applied to the imprintlithography template arrangement; or less than 2% of a total forceapplied to the imprint lithography template arrangement; or less than 1%of a total force applied to the imprint lithography templatearrangement; or substantially (i.e. plus or minus 0.5%) 1% of a totalforce applied to the imprint lithography template arrangement; orsubstantially 0% (up to 0.5%) of a total force applied to the imprintlithography template arrangement.

The imprint lithography template arrangement may be substantiallyrectangular (which includes substantially square), and the actuationarrangement may comprise three fixed abutment points arranged such that:two fixed abutment points are locatable along one side of the imprintlithography template arrangement; and one fixed abutment point islocatable along an adjacent side of the imprint lithography templatearrangement.

The controller may be configured to ensure that the provided force issuch that the cumulative force acting along the first axis, second axis,and about the third axis, is minimal during a deformation control mode(i.e. a mode in which deformation of the imprint lithography templatearrangement is taking place).

The actuation arrangement may form a part an imprint lithographytemplate holder.

The aforementioned imprint lithography template arrangement might be animprint lithography template, or an imprint lithography template holderthat is holding such a template.

According to an aspect, there is provided an method of controlling aposition and/or deformation of an imprint lithography templatearrangement, the method comprising: fixing three degrees of freedom ofthe imprint lithography template arrangement, the three degrees offreedom being: translation along a first axis parallel to a plane of theimprint lithography template arrangement; translation along a secondaxis, perpendicular to the first axis and parallel to the plane of theimprint lithography template arrangement; and rotation about a thirdaxis, perpendicular to the first and second axes; and controlling aforce provided to the imprint lithography template arrangement tocontrol a position or deformation of the imprint lithography templatearrangement, ensuring that the provided force is such that a cumulativeforce acting along the first axis, second axis, and about the thirdaxis, is minimal.

The term ‘locatable’ used to describe the position of actuators mayinclude ‘located’. For example, in some embodiments, an imprintlithography template arrangement (e.g. an imprint lithography templateholder) may be or comprise the actuation arrangement, and this imprintlithography template arrangement may be in permanent, or long-term,connection with the imprint lithography template. The actuators willthen be located on one or more sides of the imprint lithographytemplate.

According to an aspect of the present invention, there is provided animprint lithography apparatus, comprising: an imprint lithographytemplate arrangement for use in imprinting a pattern into a layer ofimprintable medium provided on a substrate; one or more actuators forpositioning and/or deforming the imprint lithography templatearrangement; a substrate stage for holding the substrate; an alignmentsensor for aligning the imprint lithography template arrangementrelative to a target portion of the substrate, the alignment sensorhaving a first detection bandwidth; a relative position sensor formeasuring a relative position between the imprint lithography templatearrangement and the substrate, the relative position sensor having asecond detection bandwidth, greater than the first detection bandwidthof the alignment sensor.

The alignment sensor might have a detection bandwidth of: less than 10Hz; or less than 5 Hz.

The relative position sensor might have a detection bandwidth of:greater than 100 Hz; or greater than 200 Hz.

The one or more actuators may comprise, or be in connection with, aforce sensor for measuring, directly or indirectly, a force applied bythe one or more actuators.

The force sensor may have a third detection bandwidth, that thirddetection bandwidth being greater than the first detection bandwidth ofthe alignment sensor.

The force sensor may be a position or current sensor.

According to an aspect, there is provided an imprint lithography method,comprising: controlling a position and deformation of the imprintlithography template relative to the substrate to achieve a position anddeformation substantially as intended; and, when the imprint lithographytemplate is positioned and deformed substantially as intended, reducinga control bandwidth related to the deformation of the imprintlithography template. This ensures that high frequency variation in thedeformation is not implemented. This may be advantageous, because a lowbandwidth alignment sensor might not be able to detect changes inposition that results from such high frequency variation, which mightotherwise cause patterns to be applied inaccurately.

The control bandwidth is an implementation bandwidth related to theimplementation of the deformation of the imprint lithography template(e.g. a control loop in which actuators for provided a deformation forceform a part).

The bandwidth may be reduced to: less than 100 Hz; less than 50 Hz; lessthan 10 Hz; less than 5 Hz; and/or, more generically, a bandwidth thatis in the detection bandwidth of an alignment sensor used in thealignment of the imprint lithography template arrangement with a targetportion of the substrate.

The method may further comprise imprinting the imprint lithographytemplate into a layer of imprintable medium provided on a substrate toform a pattern in that layer of imprintable medium; and wherein thecontrolling of the position and the deformation is undertaken: beforethe imprinting; or during the imprinting, and before the pattern isfixed into a substantially solid state; or before and during theimprinting, and before the pattern is fixed into a substantially solidstate.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: an imprint lithography template arrangement foruse in imprinting a pattern into a layer of imprintable medium providedon a substrate; one or more actuators for positioning and/or deformingthe imprint lithography template arrangement; a substrate stage forholding the substrate; an alignment sensor for aligning the imprintlithography template arrangement relative to a target portion of thesubstrate, the alignment sensor having a first detection bandwidth;wherein the one or more actuators comprise, or is or are in connectionwith, a force sensor for measuring, directly or indirectly, a forceapplied by the one or more actuators, and wherein the force sensor has asecond detection bandwidth, that second detection bandwidth beinggreater than the first detection bandwidth of the alignment sensor.

The apparatus may further comprises a control arrangement, the controlarrangement being configured to receive an output from the force sensor,and also being configured to convert this output into a position (e.g. arelative or absolute position (e.g. relative to a fixed part of theapparatus, such as a metrology frame), or a change or shift in position)of the imprint lithography template arrangement.

The alignment sensor may have a detection bandwidth of: less than 10 Hz;or less than 5 Hz.

The or each force sensor has a detection bandwidth of: greater than 50Hz; or greater than 100 Hz; or greater than 200 Hz.

Each actuator may comprise, or be in connection with, a force sensor.

The or each force sensor may be a position or current sensor.

A detection bandwidth is to be understood as a frequency at whichchanges (e.g. in position) can be detected, as opposed to animplementation bandwidth, which may be understood to be a frequency atwhich changes (e.g. in position) can be implemented. A control bandwidthmay be understood as comprising a detection bandwidth and/or animplementation bandwidth, depending on the context in which the term isused.

According to an aspect, there is provided an method of aligning animprint lithography template arrangement relative to a target portion ofa substrate, the method comprising: using an alignment sensor to alignthe imprint lithography template arrangement relative to a targetportion of the substrate, the alignment sensor having a first detectionbandwidth; using one or more force sensors, constituting a part of, orbeing in connection with one or more actuators, to determine a forceapplied to the imprint lithography template arrangement by the one ormore actuators, the force sensors having a second detection bandwidth,that second detection bandwidth being greater than the first detectionbandwidth of the alignment sensor; and determining a position, or changein position, of the imprint lithography template arrangement from thedetermination of the force, and using that position, or change inposition, in the alignment of the imprint lithography templatearrangement.

The use of the alignment sensor and the use of the force sensor may beundertaken in series or parallel.

An alignment sensor may be used to determine absolute changes inposition, (e.g. relative to a fixed point or part of an imprintlithography apparatus, such as a reference or metrology frame), whereasinformation from a force sensor may be used to determined a relativeposition, or change in position (e.g. of an imprint lithography templatearrangement, such as an imprint lithography template).

According to an aspect, there is provided an imprint lithographyapparatus, comprising: an imprint lithography template arrangement foruse in imprinting a pattern into a layer of imprintable medium providedon a substrate; a substrate stage to hold the substrate; and a gasdispensation arrangement to provide a gaseous atmosphere in which theimprinting of the pattern is to take place, the gas dispensationarrangement configured to dispense gas in an asymmetric manner in theprovision of the gaseous atmosphere.

The gas dispensation arrangement may be configured to dispense gas in anasymmetric manner in or into a region located in-between the imprintlithography template arrangement and the substrate holder and/orsubstrate.

The gas dispensation arrangement may comprise a plurality of outletsthat are asymmetrically distributed, or asymmetrically distributable,around the imprint lithography template arrangement.

The gas dispensation arrangement may comprise a plurality of outletsdistributed, or distributable, around the imprint lithography templatearrangement, the gas dispensation arrangement configured to dispense gasat different pressures at different outlets, to thus dispense gas in anasymmetric manner in the provision of the gaseous atmosphere.

The gas dispensation arrangement may comprise a plurality of outletsdistributed, or distributable, around the imprint lithography templatearrangement, the gas dispensation arrangement configured to dispense gasat different times at different outlets, to thus dispense gas in anasymmetric manner in the provision of the gaseous atmosphere.

The gas dispensation arrangement may be configured to dispense helium.

According to an aspect, there is provided an imprint lithography method,comprising: providing a gaseous atmosphere in which imprinting of apattern into a layer of imprintable medium provided on a substrate is totake place; wherein the gas constituting the gaseous atmosphere isdispensed in an asymmetric manner.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: an imprint lithography template arrangement foruse in imprinting a pattern into a layer of imprintable medium providedon a substrate, the imprint lithography template arrangement comprising,at least in use, an imprint lithography template provided with apatterned region to provide the pattern; a substrate stage to hold thesubstrate; and a contamination barrier dividing the apparatus into atleast two regions: i) a first, relatively unclean, region in which islocated a movable element; and ii) a second, relatively clean, region inwhich is located the substrate stage and, if holding a substrate, thesubstrate itself, and the patterned region of the imprint lithographytemplate.

The first region may be a generally upper region of the apparatus, andthe second region may be a generally lower region of the apparatus.

At least a portion of a reverse side of the imprint lithographytemplate, opposite to the side on which the patterned region isprovided, may be located or locatable in the second region.

In the vicinity of the at least a portion of the reverse side of theimprint lithography template, the contamination barrier may be formedfrom a material substantially transparent to actinic radiation.

The contamination barrier may comprise a tray or container locatedbetween fixed parts of the imprint lithography apparatus, to catchcontamination.

The contamination barrier may comprise a flexible member located betweenmovable parts of the imprint lithography apparatus, and/or between afixed part and a movable part of the imprint lithography apparatus.

At least a portion of the contamination barrier may substantiallysurround the imprint lithography template arrangement.

The contamination barrier may extend generally across the imprintlithography apparatus.

The movable element may be configured for use in conjunction with theimprint lithography template in providing a pattern in the layer ofimprintable medium.

The movable element may comprise one or more selected from, or anactuator for one or more selected from, the following: a part of theimprint lithography template arrangement, such as an imprint lithographytemplate holder and/or an imprint lithography template positioner; animprint lithography template holder; an imprint lithography templatepositioner; a camera; a sensor; and/or a radiation source.

According to an aspect of the invention, there is provided an imprintlithography apparatus, comprising: an imprint compartment, in which islocated an imprint lithography template arrangement for use inimprinting a pattern into a layer of imprintable medium provided on asubstrate, and a substrate stage to hold the substrate; and a print headcompartment in connection with the imprint compartment via a sealed orsealable access port, the print head compartment comprising an actuatorto move a print head from the imprint compartment into the print headcompartment, and/or to move a print head into the imprint compartmentfrom the print head compartment.

The actuator may be arranged to move an arm, the arm arranged to holdthe print head.

The actuator may be located below the arm.

The arm may be fully locatable within the print head compartment.

The print head compartment may comprise a gas shower located adjacent tothe access port.

The print head compartment may comprise a further, sealable, access portto provide access to a print head located or locatable in the print headcompartment.

At least in use, the imprint compartment may be maintained at a highergas pressure than a gas pressure within the print head compartment.

According to an aspect, there is provided an imprint lithographyapparatus, comprising: a substrate handling system to hold and/or move asubstrate, onto which a layer of imprintable medium is to be provided;wherein the substrate handling system is configured to also function asan imprint lithography template handling system.

The substrate handling system may comprise: a substrate handler to loada substrate onto a substrate stage; and/or a substrate stage.

The substrate handling system may, in use, handle a dummy substrate, thedummy substrate comprising a standard substrate and, in connection withthe standard substrate, an arrangement to accommodate an imprintlithography template, the arrangement located, in use, on an upper sideof the standard substrate.

According to an aspect, there is provided a dummy substrate for use inhandling an imprint lithography template, the dummy substrate having astandard substrate and, in connection with the standard substrate, anarrangement to accommodate an imprint lithography template, thearrangement being located, in use, on an upper side of the standardsubstrate.

The arrangement to accommodate an imprint lithography template maycomprise an abutment surface, and a biasing element to bias the imprintlithography template into contact with the abutment surface.

The abutment surface and/or the biasing element may be arranged tocontact a base region of the imprint lithography template (e.g. asopposed to a patterned region, or a mesa region on which the patternedregion is provided).

According to an aspect, there is provided an imprint lithography method,comprising: in an imprint lithography apparatus, using a substratehandling system to handle, directly or indirectly, an imprintlithography template.

The substrate handling system may handle the imprint lithographytemplate by handling a dummy substrate that is configured to accommodatethe imprint lithography template.

The imprint lithography template may be loaded on the dummy substratewith a patterned region of the imprint lithography template directedtowards the dummy substrate.

The features described above in relation to any one or more aspects ofthe invention may be used in addition to, in combination with, inreplacement of, or as an alternative to one or more features describedin relation to one or more other aspects of the invention. Definitionsor elaborations provided in respect of one or more features of oneaspect of the invention may be applicable to the same or similarfeatures (in terms of name or function) of others aspects of the presentinvention.

An imprint lithography template arrangement may be, for example: animprint lithography template holder, an imprint lithography templateholder holding an imprint lithography template, the imprint lithographytemplate itself, or a frame for holding or being in connection with animprint lithography template holder and/or an imprint lithographytemplate.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention will be described with referenceto the accompanying Figures, in which:

FIGS. 1a and 1b schematically depict examples of, respectively, hotimprint lithography, and UV imprint lithography;

FIG. 2 schematically depicts a configuration of an imprint lithographyapparatus;

FIG. 3 schematically depicts a configuration of an imprint lithographyapparatus in accordance with an embodiment of the present invention;

FIG. 4 schematically depicts a configuration of an imprint lithographyapparatus in accordance with a further embodiment of the presentinvention;

FIG. 5 schematically depicts a configuration of an imprint lithographyapparatus in accordance with a further embodiment of the presentinvention;

FIGS. 6 and 7 schematically depict an imprint lithography apparatus in afirst configuration and a second configuration, respectively, inaccordance with a further embodiment of the present invention;

FIG. 8 schematically depicts a clamp for use in holding an imprintlithography template arrangement;

FIG. 9 schematically depicts a clamp for use in holding an imprintlithography template arrangement, in accordance with an embodiment ofthe present invention;

FIG. 10 schematically depicts an underside view of the clamp of FIG. 9;

FIG. 11 schematically depicts an underside view of the imprintlithography template arrangement shown in FIGS. 8 and 9, with additionalfixed abutment points;

FIG. 12 schematically depicts an imprint lithography template relativeto a substrate, prior to release of the template from the substrate;

FIG. 13 schematically depicts an attempted release of the imprintlithography template from the substrate of FIG. 12;

FIG. 14 schematically depicts principles associated with release of theimprint lithography template from the substrate of FIG. 12, inaccordance with an embodiment of the present invention;

FIG. 15 schematically depicts forces involved in release of the imprintlithography template from the substrate of FIG. 12, in accordance withan embodiment of the present invention;

FIGS. 16 and 17 schematically depict rotation of the substrate andimprint lithography template, respectively, during the release of theimprint lithography template from the substrate of FIG. 12;

FIG. 18 schematically depicts an underside view of an imprintlithography template arrangement, including an actuation arrangement toposition and/or deform an imprint lithography template of the imprintlithography template arrangement;

FIG. 19 schematically depicts a side view of the imprint lithographytemplate arrangement of FIG. 18, together with a schematic depiction ofconnections between a signal amplifier and actuators of the actuationarrangement;

FIG. 20 schematically depicts a side-on view of the imprint lithographytemplate arrangement of FIG. 18, together with a schematic depiction ofconnections between a signal amplifier and actuators of the actuationarrangement, in accordance with an embodiment of the present invention;

FIG. 21 is a graph schematically depicting a stiffness of imprintablemedium over a period of time in which a fixation process is undertaken;

FIG. 22 is a graph schematically depicting a bandwidth of the control ofthe position and/or deformation of an imprint lithography template whenimprinted into the imprintable medium, during the fixation processdescribed in relation to FIG. 21;

FIG. 23 is a graph schematically depicting a stiffness of imprintablemedium over a period of time in which a fixation process is undertaken;

FIG. 24 is a graph schematically depicting a bandwidth of the control ofthe position and/or deformation of an imprint lithography template whenimprinted into the imprintable medium, during the fixation processdescribed in relation to FIG. 23, in accordance with an embodiment ofthe present invention;

FIG. 25 schematically depicts an underside view of an imprintlithography template arrangement, including an actuation arrangement toposition and/or deform an imprint lithography template of the imprintlithography template arrangement;

FIG. 26 schematically depicts an underside view of an imprintlithography template arrangement, including an actuation arrangement toposition and/or deform an imprint lithography template of the imprintlithography template arrangement in accordance with an embodiment of thepresent invention;

FIG. 27 schematically depicts an apparatus used in an imprintlithography method;

FIG. 28 schematically depicts an apparatus used in an imprintlithography method, in accordance with an embodiment of the presentinvention;

FIG. 29 schematically depicts an apparatus used in an imprintlithography method, in accordance with a further embodiment of thepresent invention;

FIG. 30 schematically depicts part of an imprint lithography apparatus,including a gas dispensing arrangement, in accordance with an embodimentof the present invention;

FIG. 31 schematically depicts part of an imprint lithography apparatus,including a gas dispensing arrangement, in accordance with an embodimentof the present invention;

FIG. 32 schematically depicts part of an imprint lithography apparatus,including a gas dispensing arrangement, in accordance with an embodimentof the present invention;

FIG. 33 schematically depicts part of an imprint lithography apparatus,including a contamination barrier, in accordance with an embodiment ofthe present invention;

FIG. 34 shows the same part of the imprint lithography apparatus of FIG.34, and additionally includes a schematic depiction of regions definedby, and separated by, the contamination barrier;

FIG. 35 schematically depicts an imprint lithography apparatus,comprising a print head compartment, in accordance with an embodiment ofthe present invention, and in a first configuration;

FIG. 36 schematically depicts the imprint lithography apparatus of FIG.35, in a second configuration;

FIGS. 37a-37d schematically depict an imprint lithography apparatus andmethod, in which a substrate handling system is used to handle animprint lithography template, in accordance with an embodiment of thepresent invention;

FIGS. 38a-38d schematically depict the imprint lithography apparatus andmethod shown in and described with reference to FIGS. 37a-37d , in whicha substrate handling system is used to handle a substrate; and

FIG. 39 schematically depicts an example of a dummy substrate to supportan imprint lithography template.

DETAILED DESCRIPTION

Examples of two known approaches to imprint lithography areschematically depicted in FIGS. 1a to 1 b.

FIG. 1a shows an example of so-called hot imprint lithography (sometimesadditionally or alternatively referred to as hot embossing). In atypical hot imprint lithography process or method, an imprintlithography template 2 is imprinted into a thermosetting or athermoplastic imprintable medium 4, which has been provided on a surfaceof a substrate 6. The imprintable medium 4 may, for example, be orcomprise resin. The imprintable medium 4 may be, for instance, spincoated and baked onto the substrate surface or, as in the exampleillustrated, onto a planarization and transfer layer 8 of the substrate6. When a thermosetting polymer resin 4 is used, the resin 4 is heatedto a temperature such that, upon contact with the imprint lithographytemplate 2, the resin 4 is sufficiently flowable to flow into and/oraround pattern features defined on the imprint lithography template 2.The temperature of the resin 4 is then increased to thermally cure(crosslink) the resin 4 so that it solidifies and irreversibly adopts adesired pattern (related, of course, to the pattern features of theimprint lithography template 2). The imprint lithography template 2 maythen be removed and the patterned resin 4 cooled. In hot imprintlithography employing a layer of thermoplastic polymer resin, thethermoplastic resin is heated so that it is in a freely flowable stateimmediately prior to imprinting with the imprint lithography template.It may be necessary to heat thermoplastic resin to a temperatureconsiderably above the glass transition temperature of the resin. Theimprint lithography template is brought together with the flowable resinand then cooled to below its glass transition temperature with theimprint lithography template in place to harden the pattern. Thereafter,the template is removed. The pattern will consist of the features inrelief from a residual layer of the resin which may then be removed byan appropriate etch process to leave only the pattern features. Examplesof thermoplastic polymer resins used in hot imprint lithographyprocesses are poly (methyl methacrylate), polystyrene, poly (benzylmethacrylate) or poly (cyclohexyl methacrylate). For more information onhot imprint, see e.g. U.S. Pat. Nos. 4,731,155 and 5,772,905.

FIG. 1b shows an example of UV imprint lithography, which involves theuse of a transparent or translucent imprint lithography template 10which is transmissive to UV radiation and a UV-curable liquid asimprintable medium 12 (the term “UV” is used here for convenience butshould be interpreted as including any suitable actinic radiation forcuring the imprintable medium). A UV curable liquid is often lessviscous than the thermosetting and/or thermoplastic resin used in hotimprint lithography and consequently may flow much faster to fillimprint lithography template pattern features. A quartz template 10 isapplied to a UV-curable resin as the imprintable medium 12 in a similarmanner to the process of FIG. 1a . However, instead of using heat ortemperature cycling as in hot imprint lithography, the pattern is frozenby curing the imprintable medium 12 with UV radiation 14 that is appliedthrough the quartz imprint lithography template 10 onto the imprintablemedium 12. After removal of the imprint lithography template 10, theimprintable medium 12 is etched (and/or undergoes other furtherprocessing) to, for example provide pattern features in the substrate 6.A particular manner of patterning a substrate through UV imprintlithography is so-called step and flash imprint lithography (SFIL),which may be used to pattern a substrate in small steps in a similarmanner to optical steppers conventionally used in IC manufacture. Formore information on UV imprint, see e.g. U.S. Patent ApplicationPublication No. 2004-0124566, U.S. Pat. No. 6,334,960, PCT PatentApplication Publication No. WO 02/067055, and the article by J. Haismaentitled “Mold-assisted nanolithography: A process for reliable patternreplication”, J. Vac. Sci. Technol. B14(6), November/December 1996.

Combinations of the above imprint techniques are possible. See, e.g.,U.S. Patent Application Publication No. 2005-0274693, which mentions acombination of heating and UV curing an imprintable medium.

Imprint Lithography Apparatus Configuration

FIG. 2 schematically depicts a configuration for an imprint lithographyapparatus. The imprint lithography apparatus comprises a first frame 20,which may be to as a base frame. The first frame 20 is mounted on afloor 22 via one or more gas (e.g., air) mounts 24. The gas mounts 24are used to inhibit or reduce vibrations passing from the floor 22 tothe first frame 20.

Mounted to the first frame 20 is an alignment sensor 28. Extending fromthe alignment sensor 28 and through the first frame 20 is a conduit 30to facilitate alignment. Mounted on an opposite side of the first frame20 (in a region defined by the first frame 20), at an opposite end ofthe conduit 30, is an imprint lithography template holder 32. Theimprint lithography template holder 32 holds in position an imprintlithography template 34. The alignment sensor 28 is used to align theimprint lithography template 34 with a substrate 36, or a target portionthereof.

The substrate 36 is located on (and may be held by) a first part of asubstrate stage 38. The first part of the substrate stage 38 may berotatable about x and y axes, parallel to the plane of the substrate 36,by way of one or more first actuators 40. The first actuator 40 isconnected to a second part of the substrate stage 42. Movement of thesecond part of the substrate stage 42 along a z axis, perpendicular to aplane of the substrate, may be achieved by appropriate use of one ormore second actuators 44. The second actuator 44 may be disposed, forexample, between the second part of the substrate stage 42 and asurrounding third part of the substrate stage 46. Translational movementof the third part of the substrate stage 46 along the x and y axes, aswell as rotation about the z-axis, may be achieved by appropriate use ofone or more third actuators 48. The third actuator 48 is disposedin-between the third part of the substrate stage 46 and the first frame20. The substrate stage as a whole is thus in connection with, and isthus coupled to, the first frame 20.

It will be appreciated from the above description, and FIG. 2, that thesubstrate 36 may be moved in or with 6 degrees of freedom: along the x,y and z axes, and rotated about the x, y and z axes.

In order to accurately move or position the substrate 36 relative to theimprint lithography template 34, one or more measurements 50 may be orare undertaken taken to determine, for example: the position of theimprint lithography template holder 32 or template 34 relative to thefirst frame 20; the position of the substrate 36 relative to the imprintlithography template holder 32 or template 34; and/or the position ofthe substrate stage (or, for example, a third, second, or first partthereof) relative to the first frame 20.

In some circumstances, where highly accurate application of patterns tothe imprint lithography template is not required (e.g. where micrometerpositional accuracy is required), the configuration of the imprintlithograph apparatus shown in FIG. 2 may be satisfactory. However, it isconsidered that imprint lithography will find application in fieldswhere pattern features that are to be applied to a substrate, and thealignment between patterns or features thereof, will have or require aresolution of the order of nanometers, a few tens of nanometers, andperhaps even below 10, 5, 3, 2 or 1 nanometers. Corresponding positionaland/or alignment accuracy is required, and the configuration shown inFIG. 2 may not be able to achieve this. For instance, deformation of thefirst frame 20 may affect the accuracy and/or consistency of positionalmeasures, which can result in a degradation in patterning accuracyand/or overlay performance. Deformation of the first frame 20 can becaused by any of a number of factors, for example, a release forceimparted on the first frame 20 when the imprint lithography template 34is released from imprintable medium provided on the substrate 36(referred to generically as release of the template 34 from thesubstrate 36), thermal disturbance, floor vibration, and/or movement ofthe substrate stage, or a part thereof.

It is desirable to provide a configuration of, or for, an imprintlithography apparatus which obviates or mitigates one or more of these,or other, problems.

One or more of the above mentioned, or other, problems can be obviatedor mitigated in accordance with one or more configurations for animprint lithography apparatus in accordance with an embodiment of thepresent invention.

In accordance with an embodiment of the present invention, there isprovided an imprint lithography apparatus which comprises a first frameto be mounted on a floor. A second frame is also provided, and thissecond frame is mounted on the first frame by kinematic coupling. Analignment sensor is provided which is mounted on the second frame, andis used to align an imprint lithography template arrangement (e.g. animprint lithography template, or an imprint lithography template holder,which may or may not hold an imprint lithography template) with a targetportion of a substrate. One or more position sensors are also providedto measure the position of the imprint lithography template arrangementand/or a substrate stage relative to the second frame.

The use of a second frame (which may be referred to as a metrologyframe, as opposed to the first frame, which may be referred to as a baseframe) that is kinematically coupled to the first frame reduces theimpact of any deformation of the first frame on the second frame,resulting in more accurate positional measurements.

In accordance with a related embodiment, there is provided an imprintlithography apparatus which comprises a first frame mounted on a floor.A second frame is mounted on the first frame via a vibration isolationsystem. The vibration isolation system prevents, or at least inhibits,the transmission of both low and high frequency vibrations from thefloor, and from the first frame and to the second frame. The apparatusfurther comprises, at least in use, an imprint lithography templatearrangement mounted on the second frame via a kinematic coupling. Thekinematic coupling prevents or reduces deformation of the imprintlithography template arrangement being transmitted to the second frame.The apparatus further comprises an alignment sensor mounted on thesecond frame, to align the imprint template arrangement with a targetportion of the substrate. One or more position sensors are also providedto measure the position of a substrate stage relative to the secondframe.

The combined use of the vibration isolation system and kinematiccoupling allows positional measurements to be undertaken more accuratelyand consistently, and therefore allows patterns to be applied to asubstrate more accurately and more consistently. The mounting of thealignment sensor on the second frame (in this embodiment, or any otherembodiment) may facilitate such accurate and consistent positionalmeasurement, and thus accurate and consistent pattern application.

Embodiments of the present invention will now be described, by way ofexample only, with reference to FIGS. 3 and 4. For consistency, likefeatures appearing in these Figures (or indeed earlier Figures) havebeen given the same reference numerals.

FIG. 3 shows an imprint lithography apparatus having many of thefeatures shown with reference to FIG. 2. However, and in contrast, theimprint lithography apparatus of FIG. 3 now includes a second frame 51mounted on the first frame 20 via one or more kinematic couplings 52.

At least a portion 54 of the second frame 51 extends from outside of thefirst frame 20 and into a region located within the first frame 20 (e.g.where the imprint lithography template 34 and/or holder 32 will belocated), so that positional measurements for the substrate stage 38,42, 46, and/or imprint lithography template 34 and/or holder 32 can beundertaken relative to, or using, that portion 54 of the second frame51.

Additionally, in comparison with the configuration of FIG. 2, thesubstrate stage 38, 42, 46 may comprise a further part 56 which may belocated, for instance, in-between the first part of the substrate stage38 and the second part of the substrate stage 42. The further part 56may, by appropriate actuator 58, provide additional and/or alternativefunctionality to control movement and/or position of the substrate 36.For example, the additional and/or alternative functionality may be orcomprise short or long stroke movement. One or more reference surfacesor points 59 may be used in the measurement of the relative positionbetween two movable substrate stages parts, for example the third orsecond part 42, 46 and the further part 56.

One or more position sensors may be mounted on the second frame 51, forexample the portion 54 extending into (and perhaps through) the firstframe 20, to facilitate measurement of the position of the substratestage 38, 42, 46, 56 (or a part thereof) and the imprint lithographytemplate holder 32 or the imprint lithography template 34. Furthermore,the alignment sensor 28 is mounted on the second frame 51, and not onthe first frame 20, as was the case in FIG. 2.

Due to the kinematic coupling 52 between the second frame 51 and thefirst frame 20 in FIG. 3, deformation of the first frame 20 should notresult in deformation of the second frame 50. Therefore, more accurateand more consistent positional measurements may be undertaken.

Displacement of the first frame 20 may still, nevertheless, result indisplacement of the second frame 51, which can have an effect on themeasurement of position. Additionally and/or alternatively, deformationof the second frame 51 may occur for reasons other than deformation ofthe first frame 20 to which the second frame 51 is mounted. Forinstance, deformation may result as a consequence of a thermal heat loadon the second frame 51.

Deformation associated with a thermal heat load on the second frame 51may be obviated or mitigated by using a heat shield, to shield thesecond frame 51 from such heat load. Alternatively or additionally, thesecond frame 51 may be formed at least partially from a material with alow coefficient of thermal expansion (e.g. less than or equal to 1μm/m·K), and/or desirably high thermal conductance (e.g. greater than 20W/(m·K), for example aluminum, having a thermal conductance of 200W/(m·K)). A material with a sufficiently low coefficient of thermalexpansion may be a ceramic material such as Zerodur™ or Invar™, or aceramic material such as C/SiC, SiC, SiSiC or Al₂O₃. Alternatively oradditionally, a cooling system (or, more generally, a thermalconditioning system) may be provided to cool the second frame 51.

Deformation of the second frame 51 as a result of, for example,displacement or vibration or the like of the first frame 20 may also beovercome or reduced. One way of overcoming or reducing this problemwould be to reduce the displacement or vibration of the first frame 20by appropriately mounting the first frame 20 to the floor 22. Forinstance, an appropriate mounting may be, as described above, one ormore gas mounts 24, which may result in the at least partial inhibitionof the transmission of both low and high frequency vibrations from thefloor 22 to the first frame 20, and thus inhibit or reduce thetransmission of vibrations to, the second frame 51. In an additional oralternative example, the second frame 51 may be constructed and arrangedto have internal dynamical modes that are of a high frequency, forexample typically 100 Hz or higher. (e.g. the second frame may beconstructed and arranged to have a stiff and light design).

FIG. 4 schematically depicts a configuration of an imprint lithographyapparatus in accordance with a further embodiment of the presentinvention. Again, many of the features of the imprint lithographyapparatus of FIG. 4 have already been shown in and/or described withreference to (at least in general) FIGS. 2 and 3. Those features havebeen given the same reference numerals in FIG. 4 for consistency.

FIG. 4 shares many of the features of the imprint lithography apparatusshown in FIG. 3. In contrast with the apparatus shown in FIG. 3, theapparatus shown in FIG. 4 has a second frame 60 that is mounted on thefirst frame 20 via one or more gas mounts 62. The second frame 60 islocated substantially within (or entirely within) the first frame 20,and may, for example, be mounted on a lip or ledge or the like of thefirst frame 20.

In this embodiment, the imprint lithography template holder 32 is againmounted to the second frame 60, but is now mounted to the second framevia one or more kinematic couplings 66. The first frame 20 may, in thisembodiment, be fixed to the floor 22 by one or more fixed mountings 68(e.g. bolts or the like).

The configuration of the imprint lithography apparatus shown in FIG. 4may be advantageous with respect to the configuration of the imprintlithography apparatus shown in FIG. 3. An advantage is that there is norequirement to make or take a measurement of the relative positionbetween the imprint lithography template 34 or the imprint lithographytemplate holder 32 and the second frame 60, because the imprintlithography template holder 32 (and, by appropriate holding, the imprintlithography template 34) is stably connected to the second frame 60 bythe kinematic coupling 66. A further advantage of the arrangement asshown in FIG. 4 is that movement of the substrate stage 38, 42, 46, 56will not directly excite (e.g. disturb via displacement or vibration)the second frame 60, because the second frame 60 is effectively isolatedfrom vibrations or the like of the first frame 20 (to which thesubstrate stage is least indirectly connected) by the gas mount 62.

However, there may be a disadvantage associated with the arrangementshown in FIG. 4 (at least relative to the arrangement of FIG. 3). Onedisadvantage is that when the imprint lithography template 34 isreleased from imprintable medium provided on the substrate 36 (moregenerally referred to as release of the template 34 from the substrate36), a release force will act on the second frame 60 and may displaceand/or deform the second frame 60. This is undesirable, sincemeasurements are taken relative to this second (in other wordsmetrology) frame. A way of overcoming, or at least partially overcoming,this problem is shown in FIG. 4. One or more release compensationactuators 70 are connected between the first frame 20 and the imprintlithography template holder 32. The release compensation actuator 70 maybe a Lorentz actuator, since a Lorentz actuator will not transferdeformations or displacements to the second frame. The releasecompensation actuator 70 may extend through the second frame 60 (forexample, through one or more conduits or passages or the like).Furthermore, by ensuring that a point or points of connection of the oneor more release compensation actuators is linked (e.g. in terms of aspatial or structural relationship) to a point of connection of thekinematic coupling 66 via which the imprint lithography template holder32 is mounted to the second frame 60, deformation of the second frame 60may be reduced or minimized. The point or points of connection of theone or more release compensation actuators 70 may be on opposite sidesof the imprint lithography template holder 32 to the point or points ofconnection of the kinematic coupling 66 via which the imprintlithography template holder 32 is mounted to the second frame 60. Inother words, release compensation actuator force should desirably bepassed through or via one or more connection points of the kinematiccoupling 66, so that the second frame 60 is not bent or otherwisedeformed.

In one embodiment, not shown, three release compensation actuators maybe used in order to compensate for not only release force, but movementof the force (i.e. the release force is dynamic). In an embodiment,measurement of the release force may be made, and/or measurement of acounter force provided by the release compensation actuator.

In the embodiment shown in FIG. 4, it may not be possible or practicalto mount the first frame 20 to the floor 22 via a gas mount. This isbecause a gas mount is already present in the configuration, between thesecond frame 60 and the first frame 20. Gas mounts in series may causeinstability, which is undesirable and may in fact lead to an increase inmeasured positional errors. Therefore, the first frame 20 may be fixedto the floor 22 in a relatively fixed and inflexible manner. This,however, means that the substrate stage 38, 42, 46, 56 is not isolated(in terms of vibrations or the like) from the floor 22. This may resultin the position of the substrate being affected to such an extent as toresult in degradation in the measurement of positional accuracy and, forexample, poor overlay. This problem may be overcome by providing asubstrate stage, or one or more parts of that substrate stage, which hasan isolated short stroke actuator holding the substrate such thatpositional accuracy may be preserved, despite the fact that the firstframe 20 is coupled to the floor 22 in a relatively strict manner.‘Isolated’ may mean that the stage moves or is movable in a contactlessmanner (e.g. via magnetic force and/or electrostatic force). Inpractice, a 5 degrees of freedom Lorentz short stroke substrate stagemay fulfill these requirements. A 5 degrees of freedom Lorentz shortstroke substrate stage may not be necessary with the embodiment shown inFIG. 3, because in FIG. 3 the first frame is isolated from vibrations ofthe floor via the use of a gas mount.

FIGS. 3 and 4 depict schematic arrangements for the layout of an imprintlithography apparatus. It will be appreciated that the apparatus mayhave a different layout, for example a different configuration ofsubstrate stage, while still embodying the principles of the invention.

In determining an appropriate configuration for an imprint lithographyapparatus, it is useful to consider any movement requirements ofdifferent parts of that apparatus (e.g. degrees of freedom). In oneinstance, it is desirable to be able to provide long stroke movementalong the x, y and z axes as shown in the Figures, either of the imprintlithography template arrangement, or the substrate, or both. Such longstroke movements may be used to coarsely position the template relativeto the substrate, and may be inaccurate on a nanometer scale. At thesame time, it is desirable to be able to provide accurate, short strokemovement along the x and y axes as shown in the Figures, and rotationabout the x, y and z axes. Such movement may be required for finer, andfinal, alignment of the template relative to the substrate. Suchmovement may again be provided via either of the imprint lithographytemplate arrangement, or the substrate, or both. Alignment of theimprint template relative to the substrate may be achieved byestablishing a fixed positional relationship between the alignmentsensor and the imprint template in the x and y directions. This meansthat x and y movement of the template may not be required, potentiallysimplifying the structure of the apparatus in the vicinity of thetemplate. Such simplification in the apparatus may lead to a reductionin heating and/or vibration of the imprint template arrangement (i.e. animproved stability of the imprint template arrangement), which isdesirable to, e.g., meet overlay requirements. Four systemconfigurations become apparent:

1) The substrate stage is capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes), andalong an axis perpendicular to that plane (z axis). The substrate stageis capable of rotational movement about the two axes that are parallelto the plane of the substrate (rotation about x and y axes). The imprintlithography template arrangement is capable of translational shortstroke movement along the two axes parallel to the plane of thesubstrate (x and y axes), and the imprint lithography templatearrangement is capable of rotational movement about the axis that isperpendicular to that plane (rotation about z axis).2) The substrate stage is capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes), andalong an axis perpendicular to that plane (z axis). The substrate stageis capable of rotational movement about the two axes that are parallelto the plane of the substrate (rotation about x and y axes), and aboutthe axis that is perpendicular to that plane (rotation about z axis),and the substrate stage is capable of translational short strokemovement along the two axes parallel to the plane of the substrate (xand y axes). The substrate stage is a five degree of freedom shortstroke substrate stage. For example, the substrate stage is a fivedegree of freedom isolated (e.g. spatially isolated or separated) shortstroke substrate stage. The substrate stage may additionally comprise orbe a three degree of freedom long stroke substrate stage.3) The substrate stage is capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes). Thesubstrate stage is capable of rotational movement about the two axesthat are parallel to the plane of the substrate (rotation about x and yaxes). The imprint lithography template arrangement is capable of longstroke movement along an axis perpendicular to the plane of thesubstrate (z axis). The imprint lithography template arrangement iscapable of translational short stroke movement along the two axesparallel to the plane of the substrate (x and y axes), and the imprintlithography template arrangement is capable of rotational movement aboutthe axis that is perpendicular to that plane (rotation about z axis).4) The substrate stage is capable of translational long stroke movementalong two axes parallel to a plane of the substrate (x and y axes). Thesubstrate stage is capable of rotational movement about the two axesthat are parallel to the plane of the substrate (rotation about x and yaxes), and about the axis that is perpendicular to that plane (rotationabout z axis), and the substrate stage is capable of translational shortstroke movement along the two axes parallel to the plane of thesubstrate (x and y axes). The substrate stage is a five degree offreedom short stroke substrate stage. For example, the substrate stageis a five degree of freedom isolated (e.g. spatially isolated orseparated) short stroke substrate stage. The imprint lithographytemplate arrangement is capable of long stroke movement along an axisperpendicular to the plane of the substrate (z axis). The substratestage may additionally comprise or be a three degree of freedom longstroke substrate stage.

Rotational movement will usually be of a short stroke nature.

In the embodiments described herein, the terms ‘long stroke’ and ‘shortstroke’ have been used. ‘Long stroke’ may encompass or be defined bymovement in the range of 1 μm up to 1 m or greater. ‘Short stroke’ mayencompass or be defined by movement in the range of 0.1 nm or less up toabout 1 μm, and/or rotational movement of 1 μrad or less up to 10 mrad.

The substrate stage described herein may be, may comprise, or may form apart of one or more of: a substrate holder; a positioner of thesubstrate; and/or a positioner of a substrate holder.

The first frame as described herein may be referred to as a base frame.A base frame is typically used as a force frame. Substrate stage (or thelike) and process forces act against and/or are absorbed by the baseframe. The second frame as described herein may be referred to as ametrology frame. A metrology frame is a frame against or from whichpositional measurements (or more accurate positional measurements) areundertaken. The metrology frame is thus often isolated, as far aspossible, from external vibrations and distortions and the like, to makethe metrology frame, and the associated positional measurements, asstable as possible. A base frame provides a base upon which otherapparatus may be mounted or connected, for example the metrology frame.The base frame may also be isolated from vibrations and distortions, butoften not to the same extent as the metrology frame.

Movement of one or more parts of the apparatus has been describedherein. ‘Movement’ may comprise the driving and/or guiding of suchmovement.

In the embodiments described herein, gas mounts have been described. Theuse of at least three gas mounts may be desirable, since frames areusually supported by three mounts of one type or another.

In the embodiments described herein, the term ‘gas mounts’ has beenused. Instead, and more generically, the term ‘vibration isolationsystem’ may be used in place of ‘gas mount’. A gas mount is an exampleof such a vibration isolation system. Another vibration isolation systemmay be or comprise rubber supports.

Limit Distortion of Second Frame During Release of Imprint Template

The use of a release compensation actuator (i.e. an actuator thatprovides a force, for example an opposing or compensatory force, duringrelease of an imprint lithography template arrangement from asubstrate), has already been discussed in relation to FIG. 4. In FIG. 4,the release compensation actuator was connected to the first (base)frame, and extended through the second (metrology) frame. In a moregeneric aspect, there is a provided an imprint lithography apparatuswhich comprises a base frame and a metrology frame. An imprintlithography template arrangement is in connection with the base frame orthe metrology frame via one or more kinematic couplings and one or morerelease compensation actuators. In particular, this more general aspectis not limited to the one or more release compensation actuatorsextending through the metrology frame to the base frame.

FIG. 5 shows an example of this aspect. FIG. 5 shares and shows the vastmajority of the features already shown in and referenced to FIG. 4. Incontrast to FIG. 4, however, in FIG. 5 the release compensation actuator70 extends between the imprint lithography template holder 32 and themetrology frame 60. The release compensation actuator 70 limits orprevents deformation or distortion of the metrology frame 60 when theimprint lithography template 34 is released from the substrate 36.

In FIG. 5, a point or points of connection of the one or more releasecompensation actuators 70 is or are located on opposite sides of theimprint lithography template arrangement (in this case, the imprintlithography template holder 32) to a point or points of connection ofthe kinematic coupling 66. This helps ensure that a release force on theimprint lithography template holder 32 that would otherwise have beenpassed through the kinematic couplings 66 to the metrology frame 60 maybe more readily opposed and compensated for. An alternative and perhapsadvantageous arrangement (not shown in the Figure) is one in which theone or more kinematic couplings are located in series with the one ormore release compensation actuators. For example, a kinematic couplingand a release compensation actuator may be connected to one another andboth, together, extend between the imprint lithography templatearrangement and the metrology frame (or, the base frame, in otherembodiments). This arrangement may be advantageous, as it reduces thenumber of connection points required for the kinematic coupling and therelease compensation actuator, and also helps ensure that the kinematiccoupling and release compensation actuator are in alignment with oneanother, thus allowing an opposing and/or compensatory force to therelease force to be more easily and accurately provided.

FIGS. 4 and 5 depict an apparatus for attempting to control and limitthe force applied to the metrology frame during release of the imprintlithography template arrangement from the substrate. A variant mightinvolve having the imprint lithography template arrangement notconnected to the metrology frame during the release, so that the releaseforce simply cannot be transmitted to or through the metrology frame.FIGS. 6 and 7 show how this might be implemented in practice.

FIG. 6 schematically depicts a base frame 80 and a metrology frame 82.The metrology frame 82 might be mounted on or connected to the baseframe 80 by one or more kinematic couplings, and/or gas mounts, or thelike (not shown). The apparatus further comprises an imprint lithographytemplate arrangement in the form of an imprint lithography templateholder 84 holding an imprint lithography template 86. One or moreactuators 88 (e.g. Lorentz actuators) may connect (or be used toconnect) the imprint lithography template arrangement (e.g. the imprintlithography template holder 84) to the base frame 80. The imprintlithography template holder is biased towards (i.e. into) connection(e.g. contact) with the metrology frame 82 by one or more springs 90(e.g. highly compliant preloaded springs) which are connected (e.g.,attached) to the metrology frame 82. In another embodiment, the actuator88 may provide this biasing.

In FIG. 6, the imprint lithography template arrangement is shown asbeing in a first configuration, when the imprint lithography templatearrangement is in connection with (e.g. in contact with) the metrologyframe 82. When in this first configuration, the imprint lithographytemplate arrangement (and in particular, the imprint lithographytemplate 86 thereof) may be used to imprint a pattern into a layer ofimprintable medium 92 provided on a substrate 94. The substrate 94 isheld in position, and may be moved or posited, by a substrate stage 96.Because the imprint lithography template arrangement is in contact withthe metrology frame, the position of the imprint lithography templatearrangement may be accurately determined, allowing patterns to beaccurately located and/or aligned relative to the substrate.

The pattern provided in the imprintable medium is then fixed (e.g.cured) by appropriate irradiation, heating, or the like. If thesubstrate 94 was released from the imprint lithography template 86 whenin the configuration shown in FIG. 6, a release force would be impartedon the metrology frame 82. This may cause deformation, distortion and/ordisplacement of the metrology frame which can have an impact onpositional measurement made using or relative to the metrology frame 82.This is undesirable, since this may adversely affect the positioning orlocating of patterns, or subsequently applied patterns. FIG. 7 shows howthis problem may be overcome.

In FIG. 7, and after the pattern has been fixed in the imprintablemedium 92, the imprint lithography template arrangement is shown ashaving been moved to a second configuration. In the secondconfiguration, the imprint lithography template arrangement isdisconnected from the metrology frame 82 (i.e. is not in contact withthe metrology frame 82, other than via the compliant springs 90 whichwill now be in an unloaded state), and is instead in connection with thebase frame 80. This configuration helps ensure that a release forcegenerated during release of the imprint lithography template arrangementfrom the substrate (and, for example compensated for by any releasecompensation actuators as described herein) will be imparted to the baseframe 80, and not to the metrology frame 82.

The imprint lithography template arrangement may be moved in anyappropriate way. In FIG. 7, the imprint lithography template arrangementis moved by appropriate movement of the substrate stage 96 that holdsthe substrate 94. For example, movement of the substrate may be movedtowards the base frame 80, which will cause movement of the imprintlithography template arrangement towards the base frame 80. Movement ofthe imprint lithography template arrangement toward the base frame 80 atleast partially overcomes the bias provided by the springs 90, thusmoving the imprint lithography template arrangement out of connectionwith the metrology frame 82. The actuator 88 may then be used to holdthe imprint lithography template arrangement, effectively connecting theimprint lithography template arrangement to the base frame 80 andkeeping the imprint lithography template arrangement disconnected fromthe metrology frame 82. The substrate 94 (and the fixed patterns ofimprintable medium carried by that substrate 94) will then be pulledaway from the imprint lithography template 86 (sometimes referred to aspeeling of the substrate 94) via appropriate movement of the substratestage 96 away from the base frame 80 and the imprint lithographytemplate 86.

During release, the imprint lithography template arrangement is not(rigidly) connected to the metrology frame 82. Thus, displacement and/ordistortion of the metrology frame due to the force imparted duringrelease is limited or avoided.

Movement of the imprint lithography template arrangement to disconnectit from the metrology frame, and the connection of the imprintlithography template arrangement to the base frame, may be undertaken inthe same process and/or at the same time. For example the movement andconnection may be undertaken by appropriate engagement of the one ormore actuators and movement of the substrate stage at substantially thesame time.

In a variation, there may be no need to provide an independent biasingelement in the form of a spring or the like to bias the imprintlithography template arrangement into connection with the metrologyframe. Instead, the aforementioned actuator may be capable of biasingthe imprint lithography template arrangement into connection with themetrology frame. This may be undertaken in a first mode of operation,for example during a first time period before and/or during fixing ofthe pattern in the layer of imprintable medium. In a second, subsequentmode, the actuator may be controlled to retract the imprint lithographytemplate arrangement to disconnect the arrangement from the metrologyframe, and (at the same or at a later time) hold the arrangement inposition to connect the imprint lithography template arrangement to thebase frame.

Long Burls for Imprint Lithography Template Arrangement Clamp

In an imprint lithography apparatus or method, it is often desired to beable to clamp in position (or in other words hold) an imprintlithography template arrangement. A clamping configuration may be areleasable clamping configuration so that the clamping or holding is notpermanent. Clamping may be necessary to, for example, hold in positionan imprint lithography template holder that holds, or is arranged tohold, an imprint lithography template, or to hold in position an imprintlithography template in isolation. A clamp, as opposed to a permanentconnection, may be advantageous so as to allow for interchanging ofdifferent imprint lithography template arrangements.

In one or more examples, the clamping configuration (which may compriseone or more clamps) may be, or form at least a part of, an imprintlithography template arrangement, for example an imprint lithographytemplate holder suitable to hold an imprint lithography template.

FIG. 8 schematically depicts an imprint lithography template arrangementand a clamping configuration. In this example, the imprint lithographytemplate arrangement comprises an imprint lithography template 100. Theimprint lithography template 100 comprises a base region 102 from whichprotrudes a mesa 104 on which one or more pattern features may beprovided for use in imprinting a pattern into a layer of imprintablemedium. The mesa 104 and base region 102 may be integrally formed.

One or more actuators 106 may be distributed around a periphery of thebase region 102. The actuator 106 may be used to position and/orselectively deform the imprint lithography template 100.

A clamping configuration is, in this embodiment, located on a reverse orback side of the imprint lithography template 100, on an opposite sideto the mesa 104. In this embodiment, the clamping configurationcomprises a seal frame 108 that extends around a periphery of thereverse side of the imprint lithography template 100. The clampingconfiguration further comprises a cover 110 which extends across theframe 108, enclosing a space 112 between the cover 110, the seal frame108, and the reverse side of the imprint lithography template 100. Thecover 110 may be at least partially transparent to actinic radiationthat may be used, in an imprint method, to fix a pattern provided in alayer of imprintable medium by the mesa 104 of the imprint lithographytemplate 100.

The seal frame 108 is provided with a number of short burls 114 (e.g.less than 1 mm in length) which extend from the base region 102 and intodirect physical contact with the reverse side of the imprint lithographytemplate 100. The short burls 114 are stiff in the x, y, and zdirections (i.e. along and perpendicular to the length of the burls114)—the short burls 114 are not flexible in the x, y, and z directions(i.e. along and perpendicular to the length of the burls 114). Locatedin spaces between the short burls 114 are seals 116 (e.g. o-ring sealsor the like) which extend within the space between the burls 114, andaround the seal frame 108 and thus around the periphery of the reverseside of the imprint lithography template 100. The short burls 114 and/orseal frame 108 may form a part of what is known in the art as a vacuumclamp, which may, also and/or accordingly be substantially inflexible inthe x, y, and z directions.

In use, the space 112 is brought into a reduced pressure state relativeto the pressure outside of the space 112 (i.e. relative to ambientpressure). The presence of the seal frame 108 and the combination ofshort burls 114 and seals 116 helps ensure that the reduced pressurestate within the space 112 is maintained. The reduced pressure statewithin the space 112 results in a clamping force being applied to theimprint lithography template 100, holding the template 100 in position.

Although the clamping configuration shown in FIG. 8 may be used to holdan imprint lithography template arrangement, there are one or moredisadvantages associated with the construction of that clampingconfiguration. As discussed above, the actuator 106 may be used toposition or deform the imprint lithography template 100. Deformationmight involve, for example, compression of the imprint lithographytemplate 100. However, the short inflexible burls 114 in contact withthe reverse side of the imprint lithography template 100 may provide acounteracting frictional force to any force applied by the actuator 106.The resulting interaction between the force applied by the actuator 106and the counteracting frictional force applied by the short inflexibleburls 114 may result in slip (possibly unexpected slip) and/orunpredictable distortion of the imprint lithography template 100relative to the clamping configuration, which can make it difficult toaccurately deform the imprint lithography template arrangement. Analternative or additional problem is that the seals 116 are, incomparison with the burls 114, relatively flexible.

FIG. 9 schematically depicts a clamping configuration which may at leastpartially overcome one or more of the problems associated with theclamping configuration shown in FIG. 8. Referring to FIG. 9, theclamping configuration comprises one or more clamps 120. In oneembodiment, a plurality of clamps may be provided, for example extendingand/or distributed around a periphery of the imprint lithographytemplate base region 102. In another example, and as shown in FIG. 9, asingle clamp 120 may be constructed and arranged to extend around theperiphery of the imprint lithography template base region 102. The clamp120 may be formed from a ceramic such as: SiSiC, SiC, Al2O3, or a metalsuch as: steel, aluminium & Invar™ (FeNi36).

The clamp 120 comprises a base region 122. One or more burls 124 extendfrom a base region 122 and, in use, into contact with the imprintlithography template base region 102. A space 126 surrounds the burls124. One or more seal walls 128 are provided that also extend from thebase region 122, and which surround the space 126 that surrounds theburls 124. The burls 124 extend further from the base region 122 thanthe seal wall 128, such that the seal wall 128 does not come intocontact with the imprint lithography template arrangement 100. Instead,the seal wall 128 has a length which results in a small gap beingdefined between the remote ends of the seal wall 128 and the imprintlithography template 100. For example, the burls 124 may extend 1-10 μmfurther from the base region 122 than the seal wall 108, or perhaps 3-5μm further from the base region 122 then the seal wall 128. This willresult in a gap between the remote end of the seal wall 128 and theimprint lithography template 100 of approximately 1-10 μm, orapproximately 3-5 μm. The gap is such that, in use, the seal wall 128 isconfigured to provide an at least partial seal with the imprintlithography template 100 when the space 126 is arranged to be at a lowerpressure than ambient pressure (i.e. a surrounding pressure, for examplea pressure external to the space 126). Such a reduced pressure providesa force sufficient to clamp the clamping configuration to the imprintlithography template 100.

Additionally or alternatively, the gap between the seal wall 108 and theimprint lithography template 100 may reduce contamination, frictionand/or distortion which might otherwise result from (e.g. movable)contact between the seal wall 108 and the imprint lithography template100.

In this embodiment, the burls 124 are of a length and/or shape whichresults in the burls 124 being at least partially flexible in adirection parallel to a plane of the imprint lithography template 100(for example, an x-y plane, or in other words orthogonal orperpendicular to the length of the burls 124). This at least partialflexibility in the aforementioned directions allows for predictablemovement, non distortional expansion and/or compression of the imprintlithography template 100 without slip of the burls 124 relative to theimprint lithography template 100 resulting in increased positionalaccuracy and compression of the imprint lithography template 100. At thesame time, the burls 124 are relatively stiff along their length (i.e.in the z-direction), fixing the degree of freedom in this direction,which may increase the accuracy with which changes in position and/ordeformation of the imprint lithography template 100 can be made.

In order to achieve the aforementioned flexibility, each of the burlsmay be, for example, at least 1 mm long, at least 5 mm long, at least5-10 mm long, at least 10 mm long, and/or less than 100 mm long.

In use, the space 126 surrounding the burls 124 may be at leastpartially reduced in pressure (relative to an external, ambientpressure). The small gap between the seal wall 128 and the imprintlithography template 100 is small enough to provide an at least partialseal, such that the reduced pressure space 126 provides a clamping forceto the imprint lithography template 100. Due to the reduction inpressure, a seal wall may be referred to as a vacuum seal wall, and/or aseal may be referred to as a vacuum seal.

A cover 130 might optionally be provided, that cover 130 extendingacross the clamp 120. The cover 130 may be at least partiallytransparent to actinic radiation, which may be used, in an imprintmethod, to fix a pattern provided in a layer of imprintable medium bythe mesa 104 of the imprint lithography template 100.

FIG. 10 shows an underside view of the clamping configuration of FIG. 9.It can be seen that the clamping configuration 132 comprises a pluralityof burls 124 constructed and arranged to be distributed around aperiphery of an imprint lithography template. The clamping configuration132 comprises an outer seal wall 134 that extends around an outerperimeter of a region containing the burls 124, and an inner seal wall136 that extends around an inner perimeter of the region containing theburls 124.

Due to the previously described flexibility of the burls 124,compressive forces (and the resulting or associated magnificationcorrection or the like) may be much more predictably and consistentlyprovided. Furthermore, due to the flexibility, the frictional forcesreferred to above in relation to the arrangement of FIG. 8 may not bepresent, and the related slip of the burls relative to the imprintlithography template may not occur.

Due to the inherent flexibility of these long burls, there may be arequirement to provide an additional mechanism to fix degrees of freedomof the imprint lithography template, for example in the x and ydirections (and therefore rotation about the z axis). FIG. 11 shows anunderside view of the imprint lithography template 100 shown in FIG. 9.Referring to FIG. 11, one or more actuators 106 to position or compressthe imprint lithography template 100 are shown as being distributedaround a periphery of the base region 102 of the imprint lithographytemplate 100. In order to fix the degrees of freedom of the imprintlithography template 100 in the x, and y directions, and thereforerotation around about the z axis, fixed abutment points 140 areprovided. Two of these abutment points 140 are located along one side ofthe imprint lithography template arrangement 100, and another (of thethree) abutment points 140 is located along an adjacent side of theimprint lithography template 100. This arrangement of abutment points140 helps ensure that the degrees of freedom of the imprint lithographytemplate 100 in the x and y directions may be fixed, which may assist inthe provision of accurate positioning and/or deformation of the imprintlithography template 100. This means that the clamping configurationsdescribed previously do not have to provide this fixation of the degreesof freedom, and this in turn allows the burls to be flexible in nature.

Substrate Release by Directional Peeling

After an imprint lithographic template has been imprinted into a layerof imprintable medium, a pattern provided in the layer of imprintablemedium is fixed by the application of, for example, heat or actinicradiation. When the pattern is fixed the imprint lithography templateis, at least to some extent, fixed to the substrate on which theimprintable medium is provided. In order to release the imprintlithography template from the substrate (which includes releasing theimprint lithography template from material provided on a substrate), apulling force is applied to one or both of the imprint lithographytemplate and the substrate. However, in some circumstances, theprovision of such a pulling force may result in one or more problemsbeing encountered. FIGS. 12 and 13 schematically how and why suchproblems may occur.

FIG. 12 is a side-on view of a substrate 150 provided with a layer ofimprintable medium 152. The substrate 150 is held in position by asubstrate stage 154. An imprint lithography template 156, held by animprint lithography template holder 158, is in contact with andimprinted into the layer of imprintable medium 152. A pattern providedin the layer of imprintable medium 152 has been fixed, which hasresulted in the imprint lithography template 156 being, at least to someextent, fixed to the substrate 150 via the layer of imprintable medium152.

FIG. 13 shows that in order to release the imprint lithography template156 from the substrate 150, a pulling force is applied to the substrate150 in this case by appropriate (e.g., downwards) movement of thesubstrate stage 154. If the substrate 150 was held with sufficient forceon and by the substrate stage 154, the substrate 150 and imprintlithography template 156 might be readily released from one another.However, the mechanism by which the substrate 150 is held on thesubstrate stage 154 (for example, vacuum clamping, or electrostaticclamping, or the like) may result in a holding or clamping force beingnon-uniformly distributed across the substrate 150. In some examples,this holding force might reduce in the radial direction, and is forexample greater in magnitude towards the center of the substrate 150than at a peripheral (e.g. edge) region of the substrate 150.

FIG. 13 shows that when an attempt is made to release the imprintlithography template 156 from a peripheral region of the substrate 150,a pulling force 160 provided by movement of the substrate stage 154(together with any fixation force between the imprint lithographytemplate 156 and imprintable medium 152) may exceed a holding force thatwould otherwise keep the substrate 150, or a peripheral region thereof,on the substrate stage 154. Because this holding force is exceeded, itcan be seen in FIG. 13 that the peripheral region of the substrate 150is pulled away from and out of contact 162 with the substrate stage 154.The pulling of the peripheral region of the substrate 150 away from thesubstrate stage 154 may be disadvantageous. For example, such pulling,which may result in bending of the substrate 150 and the layer ofimprintable medium 152 provided thereon, can result in damage to thesubstrate 150 or layer of imprintable medium 152, or damage to a patternprovided in or on the layer of imprintable medium 152. It is thereforedesirable to provide an apparatus and method to release an imprintlithography template from a substrate which obviates or mitigates one ormore of these, or other, problems.

FIG. 14 shows the same substrate stage 154, substrate 150, layer ofimprintable medium 152, imprint lithography template 156, and imprintlithography template holder 158 as shown in and described with referenceto FIG. 13. However, and in contrast to the arrangement shown in anddescribed reference to FIG. 13, FIG. 14 depicts principles associatedwith a different method to release the imprint lithography template 156from the substrate 150.

The imprint lithography template 156 and substrate 150 may be releasedfrom one another by pulling the substrate 150 and the imprintlithography template 156 away from one another. In FIG. 14, this isdenoted by arrow 164, which depicts a generally downward movement of thesubstrate stage 154 that holds the substrate 150. In other embodiments,the imprint lithography template 156 may be moved in an upwardsdirection by appropriate movement of the imprint lithography templateholder 158. In other embodiments, the imprint lithography template 156can be moved upwards and the substrate 150 moved downwards.

Referring back to FIG. 14, and distinguishing the release method fromthat discussed in relation to FIG. 13, in addition to pulling 164 of thesubstrate 150 away from the imprint lithography template 156, therelease method also comprises rotating 166 one or both of the imprintlithography template 156 and/or the substrate 150 toward the other ofthe imprint lithography template 156 and/or a substrate 150. Therotation (e.g. direction and/or magnitude of any force associated withsuch rotation, often described as the rotational moment, or moment) issuch that at a radial extremity of an interface between the imprintlithography template 156 and the substrate 150 (e.g. a contact area orregion between the imprint lithography template 156 and the substrate150 or the material provided thereon), there is a cumulative forceacting on the substrate 150 that results in the substrate being held onthe substrate stage (or, more particularly, that portion of thesubstrate 150 at that radial extremity being held on the substrate stage154). The rotation may alternatively or additionally be described asbeing such that a pressing force is applied to the region of thesubstrate at the radial extremity of the interface. This pressingresults in the radial extremity of the interface being pinned duringrelease, which helps prevent that portion of the substrate 150 beingpulled away from and out of contact with the substrate stage 154.

The pulling force 164 and rotating moment 166 may be undertaken in thesame manoeuvre, or at the same time, and/or by the same apparatus, forexample by appropriate movement of the imprint lithography templateholder 158 and/or the substrate stage 154.

FIG. 15 schematically depicts (by way of arrows) some of the forcesinvolved during release of the substrate in accordance with theabove-described method. A pulling force 168 (or in other words aseparating force) is applied which serves to release the imprintlithography template 156 from the substrate 150. At the same time, therotation moment helps ensure that at a radial extremity 170 of theinterface between the imprint lithography template 156 and the substrate150, a pressing force is applied into the substrate 150, keeping thatportion of the substrate 150 pinned to the substrate stage 154. Due tothe rotation moment, the pulling force 168 is applied at an oppositeside or end of the interface to the radial extremity, which causes theimprint lithography template 156 to be peeled from the substrate 150 (orthe substrate 150 to be peeled from the imprint lithography template156).

FIG. 16 shows the resultant release of the imprint lithography template156 from the substrate 150. It can be seen that the rotation moment issuch that the imprint lithography template 156 is effectively peeledfrom the substrate 150. The peeling is directional, in that the peelingis away from a center of the substrate, and toward the pinning of thesubstrate 150 at the radial extremity of the interface between theimprint lithography template 156 and the substrate 150.

FIG. 17 schematically depicts a slightly different embodiment, where theimprint lithography template 156 is rotated during release, instead ofthe substrate 150 being rotated.

In another embodiment (not shown), both the substrate and the imprintlithography template could be rotated.

The pulling and rotational forces involved in the release of the imprintlithography template from the substrate may be defined mathematically.For example, a relationship between a pulling force, or a componentthereof, acting through a center of the imprint lithography template(due to pulling of the imprint lithography template and/or pulling ofthe substrate), and a moment associated with the rotation may be definedas:F<M/(b)where F is the pulling force, or the component thereof, acting throughthe center of the imprint lithography template, M is the moment inducedby the rotation and b is a radial distance from the center of theimprint lithography template (or, more specifically, the center of theinterface between the imprint lithography template and the substrate) tothe radial extremity of the interface.

If the above-mentioned conditions are met, the portion of the substrateat the radial extremity of the interface will be pinned, and will not bepulled away from and out of contact with the substrate stage 154. Littleor no bending of the substrate will thus occur, which helps avoid or atleast limit the damage described above when no rotation of the imprintlithography template or substrate takes place during release.

The above described method may be undertaken at any particular locationon the substrate. However, the method may be particularly applicable toreleasing of the imprint lithography template from the substrate whenthe imprint lithography template is engaged with a peripheral region ofthe substrate. At this region, and as described above, one or moreholding or clamping forces applied to the substrate may be reduced inmagnitude, for example in comparison with force applied to the substrateat a more central region of the substrate. The described method may thusallow imprinting to take place at a peripheral region of a substrate(since the method facilitates release at this region) and/or may negatethe need to provide an improved (and potentially more complex orexpensive) clamping method or apparatus for that peripheral region ofthe substrate.

In order to implement the above-mentioned method, one or both of theimprint lithography template holder and substrate stage are constructedand arranged to be movable in order to a) pull the substrate and theimprint lithography template away from one another, and b) rotate one orboth of the imprint lithography template and substrate toward the otherof the imprint lithography template and substrate, such that at a radialextremity of an interface between the imprint lithography template andsubstrate, there is a cumulative force acting on the substrate thatresults in the substrate being held on the substrate stage.

Same Amplifier for Control of Opposing Actuators

FIG. 18 schematically depicts an underside view of an imprintlithography template 180. The imprint lithography template 180 comprisesa base region 182 from which extends a mesa region 184. The mesa region184 is provided with one or more pattern features which may be imprintedinto a layer of imprintable medium to form a corresponding pattern inthat medium.

A number of actuators 186 are distributed along one or more sides of theimprint lithography template 180. The actuators may be used to positionand/or deform the imprint lithography template 180. Positioning of theimprint lithography template 180 may be required to, for example,accurately locate or align a pattern provided in or on the layer ofimprintable medium. Deformation of the imprint lithography template 180may be required to, for example, correct for one or more magnificationerrors or the like. The actuators 186 may be, for example, piezoelectricactuators which, with appropriate control, allow for nanometer precisionin the positioning and/or deformation of the imprint lithographytemplate 180.

FIG. 19 schematically depicts a side-on view of the imprint lithographytemplate 180 and actuators 186 of FIG. 18. Also included, in dottedoutline, are components used in the control of signals (i.e. controlsignals) applicable to the actuators 186. The components are shown indotted outline to indicate the fact that the components may not belocated in the position shown in FIG. 19. The dotted outline thereforedepicts schematic connections between the components and the actuators186.

One of the components used in the control of signals applicable to (e.g.provided to, in use) the actuators 186 is a control unit 188. Thecontrol unit 188 provides the control signals that control the forceapplied by each actuator 186. Each actuator 186 has an associated signalamplifier 190, 192 to amplify a control signal provided by the controlunit 188 and used to control the actuators 186.

If each of the signal amplifiers 190, 192 were ‘perfect’, thenamplification of a control signal would be exactly as is intended.However, and in reality, the amplifiers 190, 192 are not perfect. Forexample, each signal amplifier 190, 192 introduces a noise component tothe control signal during amplification of that signal. This noise willnot be constant, but will vary over time, and most probably in a randommanner. Such noise in the control signals may result in the actuators186 delivering different forces to the imprint lithography template 180at different times. For example, in one mode of operation, it may bedesired that each actuator 186 provide a force of 20 N. At one point intime, due to the inherent noise of the signal amplifiers 190, 192, theapplied force might be 20.002 N, and at another time, 19.997N. It willbe appreciated that the actual values of force used in this example aresomewhat incidental—it is the variation in these forces that issignificant. Furthermore, because the amplification of control signalsis undertaken by different amplifiers 190, 192 for different actuators186, the variation in applied force may not (and most likely, will not)be consistent for groups of actuators, or all actuators 186 disposedalong one or more sides of the imprint lithography template 180. Thenoise in the control signals caused by the amplification of the controlsignal by the different signal amplifiers 190, 192 can cause one or moreproblems.

In a first problem, if the total force applied to one side of theimprint lithography template 180 is not equal to the force applied to asecond, opposite side of the imprint lithography template 180 (e.g. byopposed actuators), the imprint lithography template will not bepositioned as intended but will be positioned at a slightly different,offset position. That position will be related to the difference inforces applied to the different sides of the imprint lithographytemplate 180.

In a second, related, problem, the application of different forces todifferent sides of the imprint lithography template may result in thedeformation, or the degree of deformation, of the imprint lithographytemplate not being as intended. For example, the deformation might betoo high or low in magnitude or direction.

FIG. 20 shows how one or more problems of the above-mentioned controlmethodology and apparatus can be obviated or mitigated. FIG. 20 depictssubstantially the same side-on view of the imprint lithography template180 and actuators 186 of FIG. 19. FIG. 20 shows a plurality of actuators186 located at a first position (e.g. side) of imprint lithographytemplate 180, and a plurality of actuators 186 located at a second,opposite position (e.g., side) of the imprint lithography template 180.The same control unit 188 is also shown.

In contrast to the arrangement shown in FIG. 19, in FIG. 20 a singlesignal amplifier 194 is provided for amplifying a control signalapplicable to an actuator 186 at a first position of the imprintlithography template 180, and an actuator at a second, opposite positionof the imprint lithography template 180 (e.g. directly opposingactuators).

By providing a single signal amplifier that amplifies control signalsapplied to opposing actuators, any noise introduced by the signalamplifier is inherent in the control signals applied to both of theopposed actuators. This means that there will be no difference in thecontrol signal applied to the opposing actuators, which means that theforces applied by both actuators should also be the same (assumingappropriately and substantially similar actuator characteristics forthose actuators). Because the forces that are applied will besubstantially the same, this means that the position of the imprintlithography template should be as intended.

The inherent noise may still result in the applied forces being thesame, but of a magnitude not as intended. This may therefore stillresult in the deformation of the imprint lithography template not beingas intended. However, because the forces applied to both sides of theimprint lithography template by the opposing actuators will besubstantially the same, any correction in the applied force may be morereadily applied.

In an embodiment, the signal amplifier will amplify the signal appliedto actuators which are directly opposed (and not just simply on, e.g.,opposite sides of the imprint lithography template) which mayfacilitate, or more readily facilitate the application of substantiallyequal forces to different opposing points (e.g., sides or points onthose sides) of the imprint lithography template. A single signalamplifier may be associated with opposing pairs of actuators, opposinggroups of actuators, or opposing actuators located along an entire sideof an imprint lithography template. More than one amplifier may beprovided, each amplifier being associated with opposing pairs ofactuators, opposing groups of actuators, or opposing actuators locatedalong an entire side of an imprint lithography template.

The actuators may be piezoelectric or Lorentz actuators, which introduceonly a small amount of noise in the force that they provide for a giveninput signal (e.g. small in comparison with any noise generated by thesignal amplifiers or of other controlling electronics).

The actuators discussed above will form an actuation arrangement tocontrol the position (which includes orientation) and/or deformation (ordegree of deformation) of an imprint lithography template. In oneexample this actuation arrangement may be in fixed connection with theimprint lithography template. In one example, the actuation arrangementmay be in fixed connection with an imprint lithography template holder,which may be brought into connection with or contact with the imprintlithography template. In another example, the actuation arrangement maybe locatable in-between an imprint lithography template holder and animprint lithography template. It is likely that in most practicalembodiments, the actuation arrangement will form a part of an imprintlithography template holder.

Increase Bandwidth of Positional and/or Deformation Control of ImprintLithography Template Immediately Prior to Solidification of ImprintableMedium

An imprint lithography template is usually imprinted into a layer ofimprintable medium when that layer of imprintable medium is in asubstantially liquid and/or flowable state. Such imprinting provides apattern in that layer of imprintable medium. That pattern is then fixed(or in other words, frozen), for example by appropriate use of actinicradiation, or heat, or the like. Fixing of the pattern brings theimprintable medium into a fixed, substantially solid state. Theimprintable medium will be in a fixed, substantially solid state at theend of a fixation process, for example at the end of an irradiationprocess with actinic radiation or at the end of a heating process, orthe like. There will be a period of time during or over which theimprintable medium is not in its substantially liquid, flowable state,or a fixed, substantially solid state. Instead, over or during thisintermediate period of time, the imprintable medium will be in anintermediate state where its stiffness (e.g. represented by the Young'smodulus, E) is increasing rapidly over time.

FIG. 21 is a graph schematically depicting a change in the stiffness ofimprintable medium (represented by a log plot of Young's modulus E) overa period of time T.

At a first time 200, fixation of the imprintable medium begins, forexample by exposure of the imprintable medium to actinic radiation. At asecond, later time 202 the stiffness of the imprintable medium begins toincrease rapidly, but not instantaneously. For example, the increase maybe over a time period of less than a second, less than 500 milliseconds,less than 250 milliseconds, less than 100 milliseconds, or less than 50milliseconds, or less than 10 milliseconds, or less than 5 milliseconds.The rate and duration of the increase will depend on a number ofconditions, for example the type of imprintable medium, an intensity ofactinic radiation, a temperature of a heat source, and the like. At athird time 204 the increase in stiffness will stop, and a maximumstiffness is reached. At this point, the imprintable medium has reacheda fixed, substantially solid state.

The graph can be divided into three relatively distinct regions: a firstregion 206, when the imprintable medium is in an unfixed, substantiallyliquid and/or a flowable state; a second region 208, when theimprintable medium is in an intermediate state, increasing in stiffnessbetween the unfixed, substantially liquid and/or flowable state 206, anda fixed substantially solid state; and a third region 210 in which theimprintable medium is in that fixed, substantially solid state.

FIG. 22 is a graph schematically depicting an exemplary bandwidth B ofthe control of the position (which includes orientation) or deformationof an imprint lithography template when imprinted into a layer ofimprintable medium. The control bandwidth is depicted relative to thethree temporal regions of the graph of FIG. 21.

FIGS. 21 and 22 are now referred to in combination. Relatively highbandwidth control of the position or deformation of the imprintlithography template relative to the substrate is undertaken when theimprintable medium is in a first, substantially liquid or flowable state206. This relatively high bandwidth control continues into a time periodin which the imprintable medium is in a second, intermediate state 208(i.e. between substantially flowable and substantially fixed states).During this second, intermediate state 208, the bandwidth of the controlis reduced to a relatively low bandwidth control as the stiffness of theimprintable medium increases and reaches the substantially fixed, solidstate 210. The relatively low bandwidth control continues into theperiod for which the imprintable medium is in the substantially fixed,solid state 210.

Relatively high bandwidth control can be undertaken in the first(substantially fluid) and second (intermediate) states because, duringthe periods for which these states are in existence, the imprintablemedium has not yet solidified. Thus, the high bandwidth control doesnot, or cannot, apply or induce high forces on or in the imprintablemedium and/or on the substrate on which the imprintable medium isprovided. However, as the stiffness of the imprintable medium increases,towards the substantially fixed state, the control bandwidth must reduceaccordingly to low bandwidth control, to avoid the application orinducement of high forces in or on the imprintable medium and/or on thesubstrate itself. The avoidance of the application or inducement of highforces may be desirable for a number of reasons, for example to avoiddamage to the layer of imprintable medium or displacement of the layerof imprintable medium and/or the substrate.

The transitional phase between high bandwidth control and low bandwidthcontrol, and in particular during the intermediate state of theimprintable medium, is significant. This is because positional ordeformation errors caused or induced during the period for which thisstate exists will or may be fixed into the layer of imprintable medium.Such errors may affect pattern placement or overlay.

According to an embodiment of the present invention, tighter (e.g. moreaccurate or stricter) position and/or deformation control of the imprintlithography template relative to the substrate is undertaken during theperiod for which the imprintable medium is in the intermediate state,i.e. between liquid and solid states. This tighter (e.g. more accurateor stricter) positional and/or deformation control is achieved byincreasing the bandwidth of the control from a first, high level, to asecond, higher level, just before the imprintable medium is fixed, i.e.when the imprintable medium is in the intermediate state, and before thecontrol is reduced to a relatively low bandwidth. Such controlmethodology may help ensure that any pattern applied to the imprintablemedium is positioned (which includes oriented) or deformed (e.g. has amagnification correction) more accurately or consistently than mightotherwise have been achievable.

FIG. 23 shows the same graph as shown in and described reference to FIG.21. FIG. 24 shows the bandwidth of control of the position and/ordeformation of the imprint lithography template relative to thesubstrate during the time periods discussed in relation to FIG. 21, andthus FIG. 23. In FIG. 24, the control bandwidth is similar to that shownin and described in reference to FIG. 22. However, in FIG. 24, andduring the period for which the imprintable medium is in an intermediatestate 208 (neither substantially flowable/fluid 206 nor substantiallyfixed 210), an even higher bandwidth control 212 is undertaken, after aninitial period of high bandwidth control, and prior to the bandwidthbeing reduced to the relatively low level. Controlling the position ordeformation of the imprint lithography template relative to thesubstrate may perhaps more generically be described as comprising:

i) undertaking relatively high bandwidth control at a first level whenthe imprintable medium is in an unfixed, substantially liquid and/orflowable state 206, followed by

ii) undertaking higher bandwidth control at a second level, higher thanthe first level, when the imprintable medium is in an intermediate state208, in-between the unfixed, substantially liquid and/or flowable state206, and a fixed, substantially solid state 210, followed byiii) undertaking relatively low bandwidth control when the imprintablemedium is in a fixed, substantially solid state 210.

A transition between the higher bandwidth control at the second leveland the relatively low bandwidth control may (or desirably will) occurwhen the imprintable medium is in an intermediate state 208.

A transition between the higher and higher bandwidth control may occurwhen the imprintable medium is in an intermediate state 208.

The control of the position and/or deformation of the imprintlithography template relative to the substrate as referred to above maybe implemented by the control of one or more servomechanisms used in thepositioning or deformation of the imprint lithography template relativeto the substrate.

A possible consequence of the higher (e.g. second) level of bandwidthcontrol may be potential instability of, for example, servomechanisms orthe like that are used to implement the described control. Settings ofthe higher (second level) bandwidth control may be tuned or selected tobe below certain thresholds or the like. The tuning or selection may besuch that any instability will arise (or will be more likely to arise)at or after a time which exceeds the period of time for which the higherlevel bandwidth control is implemented. This may obviate or mitigate anyproblems that might otherwise be associated with such instability.

The control of the position or deformation of the imprint lithographytemplate relative to the substrate may involve the control of theposition or deformation of the imprint lithography template, thesubstrate, or a combination (in series and/or in parallel) of theposition and/or deformation of the imprint lithography template and thesubstrate.

When imprinting patterns into a layer of imprintable medium, it is oftendesirable to be able to accurately align these patterns with previouslyprovided, or deposited, or processed patterns underlying that layer ofimprintable medium (often referred to as overlay, or an overlayrequirement). This is often a significant requirement that needs to bemet in order to successfully construct or manufacture devices using alithographic process. Therefore, the control referred to above maycomprise, or be involved in aligning, or maintaining alignment of, theimprint lithography template arrangement relative to a target portion ofthe substrate, for example in order to meet, or more accurately meet,those overlay requirements or the like.

Reduction of Magnification Forces Applied to Imprint LithographyTemplate that are Imparted onto Positional Supports

FIG. 25 schematically depicts an underside view of an imprintlithography template 220. The imprint lithography template 220 comprisesa base region 222 from which extends a mesa region 224. The mesa region224 is provided with one or more patterns for use in imprinting acorresponding pattern into a layer of imprintable medium. Surroundingthe imprint lithography template 220 is a plurality of actuators 226which may provide suitable force to position and/or deform the imprintlithography template 220. Fixed abutment points 228 are also provided,which may alternatively be described as positional supports. Theabutment points 228 are provided to fix three degrees of freedom of theimprint lithography template 220. The three degrees of freedom aretranslation along a first axis parallel to a plane of the imprintlithography template 220 (i.e. along the x-axis), translation along asecond axis, perpendicular to the first axis and parallel to the planeof the imprint lithography template 220 (i.e. along the y-axis), androtation about a third axis, perpendicular to the first and second axis(i.e. about the z-axis).

The actuators 226 and abutment points 228 form part of an actuationarrangement.

In use, it may be desired to deform the imprint lithography template220, for example to compress the imprint lithography template 220 toimplement a magnification correction or the like. A typical compressionof the imprint lithography template 220 may be 5 ppm (parts per million)of the length of the template 220. Such compression might involve, forexample, the application of a deformation force of up to 200 N per sideof the imprint lithography template 220.

The stiffness of the imprint lithography template 220 may typically be4×10⁸ N/m. The stiffness of the fixed abutment points 228 may be of theorder of 2×10⁸ N/m. However, and in contrast, the stiffness of a contactpoint, or area or region between the imprint lithography template 220and the fixed abutment points 228 may be much lower stiffness, and forexample be in the range of 2-3×10⁷ N/m. This much lower contactstiffness dominates the stiffness for the arrangement as a whole, andmay be a point of weakness when trying to accurately position an imprintlithography template.

Suppose that the imprint lithography template positional accuracy shouldbe better than 0.2 nm. The corresponding force disturbance (e.g. noisein the force) provided by the actuators 226 should be less than 4 mN. Ithas already been described that the applied compression force could beup to 200 N and so the signal to noise ration of the actuator 226 shouldbe better than 5×10⁴. Providing an actuator with such a signal to noiseratio is far from trivial. It is desirable to avoid the requirement ofan actuator with such a high signal to noise ratio.

In accordance with an embodiment of the present invention, a controller(not shown) used to control a force provided by the one or moreactuators 226 is configured to help ensure that the provided force issuch that a cumulative force acting along the first axis, second axisand about the third axis, all as mentioned above (i.e. along the x and yaxis, and about the z-axis), is minimal. This may alternatively oradditionally be described as ensuring that the (e.g. compression) forcesacting on the imprint lithography template 220 are substantially inequilibrium. Of course, different pairs of opposing actuators 226 maystill provide different overall forces, to allow for appropriatedeformation of the imprint lithography template 220.

Reduction in the forces being applied to the fixed abutment points 228,and for example, between or through the contact points between the fixedabutment points 228 and the imprint lithography template 220, allows formore design freedom for the actuators 226 that provide that force. Thisis because the relatively low stiffness of the contact points betweenthe fixed abutment points 228 and the imprint lithography template 220is of less importance when the force acting on those points is reduced,and this allows the signal to noise ratio of the actuators 226 to belower, and thus more readily achievable, for instance usingpiezoelectric or Lorentz actuators.

‘Minimal’ in this context may be defined by the force being applied to(which includes through) one, more or all fixed abutment points 226 asbeing less than 5% of a total force applied to the imprint lithographytemplate 220, less than 4%, less than 3%, less than 2%, less than 1%,substantially 1%, or substantially 0% of a total force applied to theimprint lithography template 220. Desirably, the force being applied to(which includes through) one, more or all fixed abutment points 226 isequal to or less than 2% of a total force applied to the imprintlithography template 220. The force can be controlled to be minimal byappropriate cumulative (or holistic) consideration of the control of theactuators 226.

Since the cumulative forces acting along the first axis, second axis,and about the third axis, are minimal, there may be a need to bias theimprint lithography template 220 in to contact with the fixed abutmentpoints in order to fix the degrees of freedom, as mentioned above. FIG.26 schematically depicts a pre-loaded biasing member 230. The biasingmember 230 may comprise of an abutment surface or face, attached to aspring or other biasing element.

Alternatively or additionally, the biasing of the imprint lithographytemplate in to contact with the fixed abutment points can be achieved bythere being a non-zero deformation force (i.e. where the ‘minimal’forces referred to above are non-zero), or an additional positionalactuator may be provided.

As discussed above, there may be a non-zero compression force acting onthe fixed abutment points 228. This force may be, for example, 1% of thetotal compression forces that are provided to the imprint lithographytemplate 220. From the values given above, it can be shown that thesignal to noise ratio of each actuator 226 becomes equal to 5×10².However, it may be that the compression or deformation of the imprintlithography template 220 should be greater than 1 nm. A deformationaccuracy may be 0.2 nm or lower. In this case, the compression ordeformation force disturbance (i.e. noise in the provided force) shouldbe smaller than 40 mN. The signal to noise ratio then becomes 5×10³.This is readily achievable, and far less than the signal to noise ratiodiscussed above.

In general, an embodiment of the invention separates templatedeformation and positioning, which reduces the chances of noise in thedeformation forces having an impact on positioning.

An imprint lithography template may have one of a number of differentshapes. However, proposed and existing imprint lithography templates aretypically rectangular (which includes square). In order to fix threedegrees of freedom referred to above, three fixed abutment points may berequired. Two fixed abutment points will be locatable along one side ofthe imprint lithography template, and another fixed abutment point willbe located along an adjacent side of the imprint lithography template.

The actuators discussed above will form an actuation arrangement tocontrol the position (which includes orientation) and/or deformation (ordegree of deformation) of an imprint lithography template. In oneexample this actuation arrangement may be in fixed connection with theimprint lithography template. In one example, the actuation arrangementmay be fixed connection with an imprint lithography template holder,which may be brought into connection with or contact with the imprintlithography template. In another example, the actuation arrangement maybe locatable in-between an imprint lithography template holder and animprint lithography template. It is likely that in most practicalembodiments, the actuation arrangement will form a part of an imprintlithography template holder.

Sensing of Template Compression Forces Applied to Imprint LithographyTemplate to Improve Positioning

FIG. 27 schematically depicts a side-on view of an imprint lithographyapparatus. The apparatus comprises an alignment sensor 240. An imprintlithography template 242 is also provided, in combination with one ormore actuators 244 for use in positioning and/or deforming the imprintlithography template 242. A layer of imprintable medium 246 is providedon a substrate 248. The substrate 248 is held on a substrate stage 250.

The alignment sensor 240 may be used to align the imprint lithographytemplate 242 relative to a target portion of the substrate 248 (whichincludes the imprintable medium 246 provided thereon), for examplebefore and/or during an imprint process.

There is a problem associated with the use of the apparatus shown inFIG. 27. The actuator 244 may be used to deform, by compression, theimprint lithography template 242. Such deformation might also result ina slight change in position. The actuator 244 may have a controlbandwidth in excess of 100 Hz, which means that a change in an appliedcompressive force, and unintended change in position, can be implementedat this frequency. However, the alignment sensor 240 has a detectionbandwidth (i.e. a frequency at which change can be detected) oftypically less than 10 Hz or even less than 5 Hz. Because the alignmentsensor has a lower detection bandwidth than the (implementation) controlbandwidth of the actuator 244, high frequency positional changeresulting from the change in compressive force applied by the actuator244 may not be detectable by the alignment sensor 240. Since thealignment sensor 240 cannot detect these changes (or at least all ofthese changes), change in the position of the imprint lithographytemplate 242 which is not detected by the alignment sensor 240 will ormay not be taken into account during an imprint. This can result in apattern being inaccurately applied during an imprint lithographyprocess. It is desirable to limit or avoid this problem.

FIG. 28 schematically depicts an imprint lithography apparatussubstantially as shown in and described with reference to FIG. 27.However, in addition to the apparatus shown in FIG. 27, in FIG. 28 arelative position sensor 252 is shown. The relative position sensor 252is constructed and arranged to measure a relative position between theimprint lithography template 242 and the substrate 248. The relativeposition sensor 252 has a detection bandwidth which is greater than thedetection bandwidth of the alignment sensor 240. The relative positionsensor 252 can therefore be used to account for any shortcomings in theperformance of the alignment sensor 240, and in particular the lowdetection bandwidth of the alignment sensor 240.

Whereas the alignment sensor 240 may provide an absolute positionalmeasurement, relative to, for example, a metrology frame of theapparatus (not shown), or between a reference mark on the substrate 248and a reference mark on the imprint lithography template 242, or thelike, the relative position sensor 252 can provide relative positionalmeasurements, which can be used in the positioning of the imprintlithography template 242 relative to the substrate 248. In combination,the imprint lithography template 242 may be more accurately aligned(i.e. positioned relative) to the substrate 248 than with use of thealignment sensor 240 alone.

As discussed above, the alignment sensor may have a typical detectionbandwidth of less than 10 Hz, or even less than 5 Hz, for example a fewHertz. In contrast, the relative position sensor may have a detectionbandwidth of greater than 50 Hz, greater than 100 Hz, or greater than200 Hz.

Although not shown in FIG. 28, additional measurement functionality maybe provided in the form of one or more force sensors which mayconstitute part of, or be in connection with, the actuator 244. Theforce sensor may be used to measure, directly or indirectly, the forceapplied by the actuator 244. The force sensor may, again, have adetection bandwidth greater than that of the alignment sensor 240discussed previously. The force sensor could be, for example, a positionsensor, or a current sensor, or any other form of sensor which can beused to determine a force applied to the imprint lithography template242. A controller of the apparatus may be used to convert the forceapplied to the imprint lithography template 242 by a respective actuator244 into a position of the imprint lithography template 242 (e.g. arelative position), and this may be used in the determination of anabsolute position, and/or the positioning, of the imprint lithographytemplate 242 relative to the substrate 248.

In an additional or alternative embodiment, one or more of the above, orother, problems may be obviated or mitigated by reducing the controlbandwidth relating to the deformation of the imprint lithographytemplate.

In this additional or alternative embodiment, a method may comprisecontrolling a position and deformation of the imprint lithographytemplate relative to a substrate (e.g. a target portion of thesubstrate) in order to achieve a position and deformation substantiallyas intended. When the imprint lithography template is positioned anddeformed substantially as intended, a control bandwidth associated withthe deformation of the imprint lithography template may be reduced. Byreducing the control bandwidth related to the deformation of the imprintlithography template, the alignment sensor may more readily detectchange in position of the imprint lithography template caused by changein compressive force applied by the actuator used in the deformation ofthe imprint lithography template. Thus, the control bandwidth in thisembodiment may be an implementation bandwidth related to theimplementation of a deformation of the imprint lithography template(e.g. via a signal applied to the actuator, or a controller of theactuator).

The control bandwidth may be reduced to less than 100 Hz, less than 50Hz, less than 10 Hz, less than 5 Hz, and/or more generically, to abandwidth that is in the detection range of an alignment sensor used inthe alignment of the imprint lithography template with a target portionof the substrate.

The reduction in the control bandwidth related to the deformation of theimprint lithography template may be implemented before the imprintlithography template is implemented into the imprintable medium, duringthe imprint, or both before and during the imprint.

The use of a force sensor has already been discussed above. In anadditional or alternative embodiment of the present invention, the useof a force sensor may be used as an alternative to, or in addition to,one or more concepts previously described. FIG. 29 schematically depictssubstantially the same imprint lithography apparatus as shown in anddescribed with reference to FIG. 27. However, and in contrast with theapparatus shown in FIG. 27, FIG. 29 shows the incorporation of one ormore force sensors 254 constituting a part of, or at least being inconnection with, the actuator 244.

As discussed above, the force sensor 254 may have a detection bandwidththat is greater than the detection bandwidth of the alignment sensor240. This facilitates accurate (or more accurate) positional measurementand/or positional control of the imprint lithography template which thealignment sensor 240 alone could possibly not provide (due to itsrelatively low detection bandwidth).

The apparatus may further comprise a control arrangement (not shown)configured to receive an output from the force sensor 254, and furtherconfigured to convert this output into a position of the imprintlithography template 242. This position could be a relative or absoluteposition of the imprint lithography template, or a change or shift insuch a position. In practice, it is likely that the position will be arelative position or shift in such relative position, whereas thealignment sensor may provide an absolute positional measurement.

The force sensor may have a detection bandwidth of greater than 50 Hz,greater than 100 Hz, or greater than 200 Hz. This is in comparison withthe alignment sensor, which may have a detection bandwidth of less than10 Hz, or less than 5 Hz.

Each actuator 244 may comprise, or be in connection with a force sensor244. Each force sensor 254 may be a position sensor, or a currentsensor, or any other form of sensor which can be used to determine aforce applied to the imprint lithography template 242.

The determination of a position, or change in position of the imprintlithography template 242 via the force sensor 254 may be undertaken inparallel or in series with a positional measurement undertaken with orby the alignment sensor 240. In practice, it is likely that themeasurements will be undertaken in parallel so that there are no timeswhen only a low bandwidth detection measurement is undertaken, wherepositional inaccuracies could occur.

Dispensing of Gas in an Asymmetric Manner

In an imprint lithography method, an imprint lithography template isbrought in to contact with an imprintable medium. That imprintablemedium may be provided in the form of a plurality of droplets. Once thedroplets have been provided on a substrate, the droplets spread outuntil a continuous layer is formed. In a first phase, the droplets canspread out freely, driven by the equilibrium of surface tension forcesand viscous drag forces until the droplets touch each other. When thedroplets begin to touch each other, gas present in or forming a gaseousatmosphere in which the imprint lithography method takes place (e.g.air) is trapped between the droplets, the substrate, and imprintlithography template. These trapped pockets of gas are sometimesreferred to as inclusions or gas inclusions. In a second phase, thesegas inclusions dissolve. The gas inclusions dissolve by diffusion of thegas in the inclusion through and/or into one or more of the imprintablemedium itself, the substrate and/or the imprint lithography template.Ideally, all of the gas inclusions should dissolve as quickly aspossible, so that a next step in the imprint lithography process cantake place as soon as possible. If the gas inclusions do not dissolve atall, the inclusions may form defects in an applied pattern.

A problem that may be encountered when undertaking an imprintlithography method in air (e.g. when the gaseous atmosphere comprisesair) is that the air may take a prolonged period of time to diffuse intothe imprint lithography template and/or substrate and/or the imprintablemedium. In an attempt to at least partially overcome this problem, a gasother than air may be used to form the gaseous atmosphere in which theimprinting of a pattern is to take place. The gas used to form thegaseous atmosphere is specifically chosen for its ability to quickly (orat least more quickly than air) diffuse into one or more of the imprintlithography template, the substrate, and/or the imprintable mediumitself. The faster diffusion results in a faster imprint lithographymethod. A gas that has been proposed for use in this manner is heliumdue to its ability to diffuse more easily than air into an imprintlithography template (e.g. a template formed from quartz or fusedsilica).

FIG. 30 schematically depicts an under side view of an imprintlithography template arrangement for use in imprinting a pattern into alayer of imprintable medium provided on a substrate (the substrate notbeing shown in the Figure). In this example, the imprint lithographytemplate arrangement comprises an imprint lithography template. Theimprint lithography template comprises a base region 260 from whichprotrudes a mesa 262 on which one or more pattern features may beprovided for use in imprinting a pattern into a layer of imprintablemedium provided on a substrate. The mesa 262 and base region 260 may beintegrally formed.

Surrounding the imprint lithography template is a gas dispensationarrangement 264 to provide a gaseous atmosphere in which atmosphere theimprinting of a pattern is to take place. The gas dispensationarrangement 264 may, for example, form part of, or be attached to, animprint lithography template holder used in the holding (and themovement and the like) of the imprint lithography template. In anotherexample, the gas dispensation arrangement 264 may be separate from theimprint lithography template holder. The gas dispensation arrangement264 comprises one or more gas outlets 266 distributed around the imprintlithography template. In another embodiment, the one or more gas outlets266 may be distributable around the imprint lithography template, forexample by appropriate movement or the like of the outlet. In anembodiment, the gas outlets 266 are distributed symmetrically about acenter of the imprint lithography template, for example relative to acenter of the mesa 262 of the imprint lithography template. Forinstance, outlets 266 on opposite sides of the mesa 262 are locateddirectly opposite one another, and are aligned with the center of themesa 262.

The gas dispensation arrangement 264 may further comprise a skirt or thelike 267 which may, in use, at least partially surround or envelop orthe like a region located between the imprint lithography template andthe substrate, to retain, or at least promote the retention of, the gasdispensed by the gas dispensation arrangement 264.

In use, gas (for example helium) will be dispensed from the outlets 266to purge air or the like from a region located in-between the imprintlithography template arrangement and the substrate holder and/or asubstrate held thereon. The intention is that, by doing this, heliumwill form the gaseous atmosphere in which imprint takes place, and notair. However, due to the symmetric distribution of the gas outlets 266about the imprint lithography template, air in the middle of the imprintlithography template (e.g. in the middle of the mesa 262) may not bereadily purged (e.g. removed). This is because the gas pressure isprovided in a symmetric manner. The air becomes trapped, because the gaspressure provided by the gas dispensation arrangement 264 is the sameall the way around the center of the mesa 262 (e.g. the gas pressure isapplied equally and symmetrically from all four sides of the gasdispensation arrangement 264, relative to the center of the mesa 262).If the air becomes trapped, any inclusions comprising air will takelonger to dissolve than inclusions containing helium. This may slow downthe imprint lithography process.

According to an embodiment, a problem discussed above may be at leastpartially overcome by dispensing gas in an asymmetric manner. Dispensinggas in asymmetric manner reduces or eliminates the possibility of thegas pressure surrounding the center of the imprint lithography templatearrangement being the same. Due to the asymmetry, any gas or the like(e.g. air) that is to be displaced by the gas introduced by the gasdispensation arrangement (e.g. helium) may more readily escape or bedisplaced from the center of the imprint lithography templatearrangement.

FIGS. 31 and 32 will be used to describe embodiments of the presentinvention. Features appearing in FIGS. 31 and 32, and already shown inand described with reference to FIG. 30, are given the same referencenumerals for clarity and consistency.

FIG. 31 shows that in order to dispense gas in an asymmetric manner, thegas outlets 266 may be distributed (if the gas outlets 266 are fixed inposition) or distributable (if the gas outlets 266 are movable) in anasymmetric manner, relative to the center of the imprint lithographytemplate (e.g. the mesa 262 thereof). For instance, it can be seen thatgas outlets 266 on opposite sides of the gas dispensation arrangement264 are not located directly opposite one another, and/or are notaligned with the center of the imprint lithography template.

Gas may be dispensed or introduced in an asymmetric manner byappropriately asymmetrically distributed gas outlets 266, as for examplealready shown in and described with reference to FIG. 31. Alternativelyand/or additionally, the asymmetric manner of the gas dispensation maybe achieved in one of a number of a different ways, even if the gasoutlets 266 are symmetrically distributed about the imprint lithographytemplate.

FIG. 32 shows a situation where the gas outlets are distributedsymmetrically about the mesa 262 of the imprint lithography template.When the gas outlets 266 are distributed in this symmetrical manner, theasymmetrical nature of the gas dispensation may be achieved using two(at least) different approaches. In the first approach, the gasdispensation arrangement 264 may be configured to dispense gas atdifferent pressures at different outlets 266, to thus dispense gas in anasymmetric manner. In a second, alternative or additional approach, thegas dispensation arrangement 264 may be configured (e.g. appropriatelycontrolled) to dispense gas at different times at different outlets, tothus dispense gas in an asymmetric manner.

Using one or more of the embodiments shown in and described withreference to FIGS. 31 and 32, or combination thereof, gas that should bepurged from the center of the imprint template arrangement (e.g. air),and which would otherwise be trapped or more readily trapped ininclusions, may be purged more readily and replaced with gas provided bythe gas dispensation arrangement (e.g. helium). This results in areduction in the time taken for any gas inclusions (e.g. at the centerof the imprint template arrangement) to dissolve, thus decreasing thetime taken to implement an imprint lithography method.

Contamination Barrier Separating a Relatively Dirty Region from aRelatively Clean Region

It is desirable to limit the amount of contamination generated in alithographic apparatus (optical or imprint based) in order to limit theeffect that any such contamination might have on the application ofpatterns to a substrate. Contamination may be externally generated, forexample in the form of dust or particulate matter that might enter theapparatus. However, contamination may also be generated internally,within a lithographic apparatus. Contamination may be generatedinternally, for example, by the movement or the like of an actuator or apart of the apparatus that the actuator controls, for example a clamp, apositioner, a holder, a camera and the like.

In optical lithography, the effect of internally generated contaminationmay be reduced by having any (or most) movable elements that maygenerate such contamination be located below the level of the substrate.Generated contamination will generally fall, under the influence ofgravity and/or any provided gas down flow, below the level of thesubstrate, thus reducing or eliminating the possibility of thecontamination falling onto the substrate. In optical lithography, thismay be readily achievable since it may be readily possible to design andconstruct an optical lithographic apparatus where most, if not all, ofthe moving parts are located below the level of the substrate. However,in imprint lithography, this may not readily achievable, due to the needto provide one or more movable elements used in an imprint lithographyprocess, or one or more actuators for those movable elements, above thelevel of the substrate. Such movable elements and/or actuators may alsobe located at or above the level of an imprint lithography template usedto imprint patters onto the substrate. Such movable elements may, forexample, comprise a part of the imprint lithography templatearrangement, an imprint lithography template holder, an imprintlithography template positioner (which may be, or constitute part of, animprint lithography template holder), a camera, a sensor, or a radiationsource. In general, one or more movable elements may be provided whichare configured for use in conjunction with the imprint lithographytemplate in providing a pattern in a layer of imprintable medium.

As discussed above, movable elements located above the level of thesubstrate, and in some examples above the level of the imprintlithography template, may generate contamination that will fall, undergravity, on to the imprint lithography template (and in particular, thepatterned region of that template) and/or the substrate. It is desirableto reduce or eliminate the contamination of the substrate and/or theimprint lithography template from a source of contamination in the formof a movable element and/or an actuator therefor.

According to an embodiment of the present invention, a problem describedabove may be at least partially obviated or mitigated by providing acontamination barrier that divides the lithographic apparatus into atleast two regions (e.g. the at least two different regions are separatedby the contamination barrier). The two regions comprise a first,relatively unclean, region in which is located one or more movableelements. The one or more movable elements will most likely beconfigured for use in conjunction with an imprint lithography templatefor use in providing a pattern in a layer of imprintable medium (e.g.imaging, moving, deforming or the like of the template). A second,relatively clean, region, separated from the first, relatively unclean,region, contains the substrate stage, and, if holding a substrate, thesubstrate itself, and a patterned region of the imprint lithographytemplate (which may be provided on a mesa of the imprint lithographytemplate). The purpose of the contamination barrier is to help preventcontamination generated by a movable element in the first region frompassing into the second region, where contamination of the substrate,substrate holder, and/or patterned region of the imprint lithographytemplate could otherwise take place. The first region will, usually, bea generally upper region of the imprint lithography apparatus, and thesecond region will, usually, be a generally lower region of the imprintlithography apparatus. It is desirable to keep a lower region of theimprint lithography apparatus clean (or as clean as possible) since thisis the region in which the substrate will be located, and also, in use,the imprint lithography template, both critical components in theimprinting of patterns. The upper region will, as described above forimprint lithography, usually contain one or more movable elements foruse in conjunction with an imprinting process or method.

FIG. 33 shows an imprint lithography apparatus in accordance with anembodiment of the present invention. The imprint lithograph apparatuscomprises an imprint lithography template 270 provided with a patternedregion 272 for use in imprinting a pattern into a layer of imprintablemedium 274 provided on a substrate 276. The apparatus further comprisesa substrate stage 278 to hold and/or move the substrate 276. Thesubstrate stage 278 may be moved, positioned or the like using one ormore actuators 280 located under, adjacent or around the substrate stage278, and below the level of the substrate 276. Since the actuators 280are located below the level of the substrate 276, contaminationgenerated by the actuators 280 will generally thus fall under gravity,and any downwardly directed gas flow, below the level of the substrate276 and will thus not contaminate the substrate 276 or the imprintablemedium 274 provided thereon.

An imprint lithography template holder 282 is also provided which isactuated by one or more actuators 284. The actuators 284 and imprintlithography template holder 282 are both located above the substrate276, and may also be located above the patterned region 272 of theimprint lithography template 270. Thus, contamination generated bymovement of the actuator 284 and/or imprint lithography template holder282 may fall in a downward direction and into contact with the substrate276, imprintable medium 274 and/or patterned region 272 of the imprintlithography template 270. In order to help prevent such contaminationfrom making such contact, a contamination barrier is provided whichdivides (i.e. separates) the imprint lithography apparatus into at leasttwo regions.

FIG. 34 shows the same apparatus as shown in FIG. 33 but, in addition,also shows the separation 286 (or in other words division ordelineation) provided by the contamination barrier between a first,relatively unclean, region 288 and a second, relatively clean region290.

FIGS. 33 and 34 will now be referred to in combination. The first region288 is a generally upper region of the imprint lithography apparatus andthe second region is a generally lower region of the imprint lithographyapparatus. Located in the first region 288 are the actuators 284 for theimprint lithography template holder 282. Located in the second region isthe patterned region 272 of the imprint lithography template 270, thesubstrate 276, and the layer of imprintable medium 274 provided on thatsubstrate. Dividing or separating the two regions 288, 290 is thecontamination barrier.

Located between fixed parts of the imprint lithography apparatus (forexample parts of a base frame 292 or the like, and another, for example,secondary frame 294 or the like) is/are one or more trays or containers296 which form a part of the contamination barrier. The trays orcontainers 296 are provided to catch contamination generated by movementof, for example, the actuators 284, and thus help prevent contaminationgenerated by the actuators 284 from reaching the second, relativelyclean region 290.

Parts of the contamination barrier located in-between movable parts ofthe imprint lithography apparatus, or between a fixed part and a movablepart of the imprint lithography apparatus, may be formed from one ormore flexible members, to allow for movement of the movable parts of theapparatus. For instance, such flexible members 298 may be locatedbetween a part of the imprint lithography template holder 282 that ismovable, and one or more relatively fixed structures, for example thesecondary frame 294 and/or another fixed structure 300. The flexiblemembers may be, for example, expandable, contractible, and/or elastic innature, or the like, in order to accommodate movement of the movablepart of the imprint lithography apparatus.

Together, the trays or containers 296 and the flexible members 298(together with parts of the apparatus to which these components areattached) form a barrier that extends around the imprint lithographytemplate 270, and generally across at least a portion of the imprintlithography apparatus, thus defining, dividing or at least separatingthe two regions 288, 290.

FIGS. 33 and 34 depict a further advantageous feature, wherein at leasta portion of the reverse side of the imprint lithography template 270may be located or locatable (for example when the imprint lithographytemplate 270 is loaded into an imprint lithography apparatus) in thesecond region 290. This may be achieved by the appropriate configurationof the contamination barrier. For example, as shown in the Figures, inthe vicinity of at least a portion of the reverse side of the imprintlithography template 270, the contamination barrier may include (or atleast a part of the contamination barrier may be formed from) material302 that effectively separates the portion of the reverse side of theimprint lithography template 270 from the first, relatively unclean,region. The material might be substantially transparent to actinicradiation. The actinic radiation may be provided by a radiation source304, and may be used to fix or freeze a pattern provided in the layer ofimprintable medium 274 during imprinting, even when the contaminationbarrier is present.

By configuring the contamination barrier in the manner described above,the contamination barrier extends more or less continuously across theimprint lithography apparatus and above a position in which the imprintlithography template 270 would be, in use, loaded. This means that evenwhen the imprint lithography template 270 is not loaded in the imprintlithography apparatus, the integrity of the contamination barrier ismaintained, and the division, or separation, or delineation between thetwo regions 288, 290 is correspondingly maintained.

In other embodiments (not shown) the contamination barrier across theimprint lithography apparatus may be maintained in a different manner,for example without the use of the material transparent to actinicradiation. For example the contamination barrier might be maintained ormaintainable by one or more movable components, which are for instancemoved into a barrier position when no imprint lithography template ispresent in the imprint lithography apparatus.

Contamination may need to be extracted from the imprint lithographyapparatus. The contamination may be extracted, for example, by an outletin connection with the first region to limit or avoid contaminationbeing drawn into the second region. The contamination may be removed byuse of an appropriate gas flow, or a reduced extraction pressure. In anembodiment, the contamination extraction could be achieved by removal ofthe one or more trays or containers from the imprint lithographyapparatus, for example through the aforementioned outlet in connectionwith the first region.

The presence of the contamination barrier limits or reduces the amountof contamination that may be passed through to a lower region of theimprint lithography apparatus in which the substrate stage and/orpatterned region of the imprint lithography apparatus are, in use,present. This barrier thus limits the chance of one or more of thesecomponents becoming contaminated. The avoidance or limitation of suchcontamination may improve the accuracy, or consistency, or yield ofpattern application, and is therefore clearly desirable.

Moving a Print Head into and Out of an Imprint Compartment

An imprint lithography apparatus may comprise one or more print heads.The print heads provide imprintable medium onto a substrate. The printheads are located or locatable within the imprint lithographicapparatus, because the imprintable medium should be provided on thesubstrate (or on certain target portions thereof), just before animprint takes place.

For maintenance, replacement or inspection of such a print head, theimprint lithographic apparatus would be opened, and for example exposedto an external environment. This can be a time-consuming and frustratingtask for an operator of the imprint lithography apparatus, and perhapsmore importantly, provide an opportunity for contamination from theexternal environment to enter the imprint lithography apparatus. It isdesirable to reduce the manual involvement of the operator, for exampleto reduce cost, wasted time, and to avoid the risk of human erroraffecting the imprint lithography apparatus. It is also desirable tolimit the amount of contamination that can enter the imprint lithographyapparatus, since such contamination can adversely affect the imprintingof patterns.

According to an embodiment, one or more of the above-mentioned problemscan be obviated or mitigated. According to an embodiment, an imprintlithography apparatus comprises an imprint compartment, in whichimprinting takes place, and in which is located an imprint lithographytemplate arrangement for use in imprinting a pattern into a layer ofimprintable medium provided on a substrate. A substrate stage is alsoprovided to hold (and, for example, move) the substrate. A (for example,separate and distinct) print head compartment is also provided. Theprint head compartment is in connection with the imprint compartment viaa sealed or sealable access port. The print head compartment comprisesan actuator to move a print head from the imprint compartment and intothe print head compartment, and/or to move a print head into the imprintcompartment from the print head compartment. This apparatus has one ormore advantages, as will be discussed in more detail below in relationto FIGS. 35 and 36 which show such an imprint lithography apparatus infirst and second configurations, respectively.

FIG. 35 shows an imprint lithography apparatus in accordance with anembodiment of the present invention, the apparatus being in a firstconfiguration. The imprint lithography apparatus comprises an imprintcompartment 310. Located in that imprint compartment 310 is apparatus312 for use in imprinting a pattern into a layer of imprintable mediumprovided on a substrate 316. That apparatus 312 may comprise, forexample, an imprint lithography template arrangement (e.g. an imprintlithography template holder and/or an imprint lithography template). Theimprint compartment 310 further comprises a substrate stage 314 to hold,in use, a substrate 316 on which imprintable medium is provided, or isto be provided, by a print head.

The imprint lithography apparatus further comprises a print headcompartment 318. The print head compartment 318 is located outside ofthe imprint compartment 310. The print head compartment 318 is inconnection with the imprint compartment 310 via a sealed or sealableaccess port 320.

The print head compartment 318 comprises an actuator 322 to move a printhead 324 into the imprint compartment 310 from the print headcompartment 318, via the access port 320. The actuator is also used tomove the print head 324 from the imprint compartment 310 and into theprint head compartment 318, again via the access port 320. FIG. 35 showsthe imprint lithography apparatus in a first configuration, where theprint head 324 is located in the print head compartment 318. FIG. 36shows the imprint lithography apparatus in a second configuration, wherethe print head 324 has been moved out of the print head compartment 318and into the imprint compartment 310, for example in order to provideimprintable medium or the like on the substrate 316. FIGS. 35 and 36will be referred to in combination.

The use of an actuator 322 to move the print head 324 into and out ofthe imprint compartment 310 allows such movement to be automated. Thislimits or negates the need for an operator to manually undertake thistask. Furthermore, and perhaps more importantly, since the print head324 is moved into and out of the imprint compartment 310 via a sealed orsealable access port 320, contamination entering the imprint compartment310 is limited.

The actuator 322 is in connection with and is arranged to move an arm326. The arm 326 is arranged to hold the print head 324 (via anappropriate electrostatic, magnetic, or mechanical holdingconfiguration, or the like). Appropriate movement and/or positioning ofthe arm 326 will allow appropriate positioning of the print head 324,and/or movement of the print head 324 within the imprint compartment310, for example to move the print head to an appropriate location forimprinting imprintable medium on to a target portion of the substrate.In use, and as can be seen in FIG. 36, the sealed or sealable accessport 320 provides a seal around the arm 326 when the arm extends throughthe access port 320. Such sealing limits or prevents contamination fromentering the imprint compartment 310 when the arm extends through theaccess port 320.

The actuator 322 is shown as being located beneath the arm 326.Contamination generated by the actuator will usually, under the force ofgravity, fall downwards. Since the actuator 322 is located beneath thearm 326, the amount of contamination that can fall from the actuator 322and on to the arm 326 is limited. Furthermore, the general provision ofthe actuator 322 outside of the imprint compartment 310 helps ensurethat contamination generated by operation of the actuator 322 is keptwithin the print head compartment 318, as opposed to entering andcontaminating the imprint compartment 310.

As shown in FIG. 35, the arm 326 may be fully locatable (e.g.retractable by the actuator 322) within the print head compartment 318.This allows the access port 320 to be fully closed, when, for exampleimprinting takes place, reducing the entry of contamination into theimprint compartment 318. This also allows the print head compartment 318to be a separate, independent module which may be manufactured, sold anddistributed separately from the imprint compartment 310. A print headcompartment may be retrofitted to an imprint compartment.

The imprint lithography apparatus may further comprise a gas shower 328located within the print head compartment 318, and located adjacent tothe access port 320. The gas shower 328 may be constantly in use, or mayonly be used (e.g. arranged to provide an air flow, or a flow of anothergas) when the print head 324 is being moved into and/or out of the printhead compartment 310. The use of the gas shower 328 provides anadditional level of contamination reduction within the imprintcompartment 310. This is because the gas shower will dislodgeparticulate contamination and the like from the print head 324 and/orthe portion of the arm 326 that passes within a region of gas flowprovided by the gas shower 328, thus preventing, or reducing the risk ofcontamination entering into the imprint compartment 310.

The print head compartment 318 may comprise a further, sealable, accessport. The access port comprises an opening 330 which may be selectivelyclosed via a door 332 or the like. The further access port providesaccess, for example, to the print head 324, for example for inspection,replacement and/or maintenance or the like.

At least in use, the imprint compartment 310 may be maintained at ahigher gas pressure than a gas pressure with the print head compartment318. This relative over pressure in the imprint compartment 310 shouldprevent most, if not all, gas born contamination passing from the printhead compartment 318 to the imprint compartment 310, and thus provides afurther level of contamination reduction or suppression.

In an embodiment not shown, the print head compartment may include astore for one or more print heads. The actuator discussed above, oranother actuator, may be configured to transfer a print head from thearm to the store, and/or from the store to the arm, to be able toselectively control which print head is movable into the imprintcompartment. This may be advantageous for maintenance purposes or thelike, or when a different print head is required, for example a printhead that can provide a different resolution of printing or the like.

In an embodiment not shown, the imprint lithography apparatus maycomprise more than one print head compartment. Using more than one printhead compartment, one or more print heads may be located in a firstprint head compartment for servicing, inspection or the like, while atthe same time another print head compartment could be in a configurationsuch that a print head has been moved into the imprint compartment foruse in providing imprintable material onto a substrate. Such anarrangement may reduce the time for which the imprint lithographyapparatus as a whole is unusable for imprinting, and thereby may be usedto increase throughput of the apparatus.

Handling, at Least Indirectly, of an Imprint Lithography Template Usinga Substrate Handling System

In an imprint lithography apparatus and method, a substrate is held, andmoved around the imprint lithography apparatus (i.e. the substrate ishandled). Furthermore, and distinct from, for example, opticallithography, the patterning device itself (e.g. an imprint lithographytemplate) may be moved around (e.g. in and out of) an imprint chamber inwhich imprinting is to take place. Such movement may be required toprovide a different imprint lithography template, for example a templatewith a different pattern. It is currently proposed to provide an imprintlithography apparatus which comprises a substrate handling system, tohandle substrates, and also an imprint lithography template handlingsystem, to handle imprint lithography templates. The provision ofseparate, distinct handling systems for the substrate and imprintlithography template, respectively, may increase the footprint of theimprint lithography apparatus, and/or the cost of the imprintlithography apparatus.

According to an embodiment, one or more of the problems referred toabove may be obviated or mitigated. According to an embodiment, there isprovided an imprint lithography apparatus and/or method in which thesubstrate handling system to handle a substrate (e.g. hold and/or movethe substrate) is configured to also function as an imprint lithographytemplate handling system (i.e. the substrate handling system is, in use,also used as an imprint lithography template handling system). By usingthe substrate handling system in this manner, there may be no need for aseparate, distinct imprint lithography template handling system. Thismay result in a reduction in cost and/or a footprint of imprintlithography apparatus, for example in comparison with an imprintlithography apparatus in which there is provided a separate, distinctimprint lithography template handling system.

FIGS. 37a to 37d , and FIGS. 38a to 38d , will be used to describe animprint lithography apparatus and method in accordance with anembodiment of the present invention. The same features appearing indifferent Figures have been given the same reference numerals, forconsistency and clarity.

FIG. 37a schematically depicts an imprint lithography apparatus. Theapparatus is divided into two compartments: an imprint compartment 340,where imprinting takes place; and a storage compartment 342, wherestorage of one or more substrates 344 and/or one or more dummysubstrates 346 takes place. A dummy substrate 346 is capable ofaccommodating an imprint lithography template 348. The substrate 344 anddummy substrate 346 may be stored on one or more storage racks 350 orthe like.

Located in the imprint compartment 340 is an imprint lithographytemplate holder 350 to hold one or more imprint lithography templates348. Also located in the imprint compartment 340 is a component of asubstrate handling system in the form of a substrate stage 352. Thesubstrate stage may be movable within the imprint compartment 340. Theimprint compartment 340 also comprises a print head 354 to provideimprintable medium on a substrate 344 onto which patterns are to beimprinted.

Another component of the substrate handling system is a substratehandler 356, which may comprise one or more robotic arms or the like.The substrate handler 356 may be located in the imprint compartment 340or the storage compartment 342. In this embodiment, the substratehandler 356 is located in the storage compartment 342.

The substrate handling system 352, 356 is provided to handle thesubstrate 344 and the dummy substrate 346, moving them around theimprint lithography apparatus. Ordinarily, a substrate handling systemwould be used solely for the handling of substrate 344 onto which apattern is to be imprinted, or on which a pattern has been imprinted.However, in accordance with an embodiment of the present invention, thesubstrate handling system 352, 356 is also used to handle dummysubstrate 346. Dummy substrate 346 is arranged to accommodate (e.g.hold, or retain in position) an imprint lithography template 348. Thus,the substrate handling system 352, 356 may therefore be used to handle(in this embodiment, indirectly) imprint lithography template 348, thusavoiding the need to provide a separate imprint lithography templatehandling system.

FIG. 37b shows that the substrate handler 356 has been used to move adummy substrate 346, with an imprint lithography template 348accommodated thereon, from the storage rack 350 and into the imprintcompartment 340. The substrate stage 352 has been moved into thevicinity of the substrate handler 356 so that the substrate handler 356may load the dummy substrate 346 onto the substrate stage 352.

FIG. 37c shows that that the substrate stage 352 may then be moved intoalignment, or approximate alignment, with the imprint lithographytemplate holder 350.

FIG. 37d shows that by appropriate movement of one or both of thesubstrate stage 352 and the imprint lithography template holder 350, theimprint lithography template 348 accommodated by the dummy substrate 346is brought into engagement with the imprint lithography template holder350. Appropriate actuation of the imprint lithography template holder350 may then be used to hold the imprint lithography template 348,allowing the dummy substrate 348 to be separated from the imprintlithography template 348.

FIGS. 37a to 37d thus show how a substrate handling system 352, 356 maybe used to handle an imprint lithography template 348 (for example, inan indirect manner).

After the imprint lithography template 348 has been held by the imprintlithography template holder 350, and the dummy substrate 348 separatedfrom the imprint lithography template 348, the dummy substrate 346 maybe, for example, moved back in to the storage compartment 342. This maybe undertaken by appropriate movement of the substrate stage 352 (onwhich the dummy substrate 346 is held) and appropriate use of thesubstrate handler 356. Such operation of the imprint lithographyapparatus results in the apparatus being in a configurationsubstantially as shown in FIG. 38a . In FIG. 38a , it can be seen that adummy substrate 346 is now located in the storage rack 350, but that thedummy substrate is not accommodating an imprint lithography template(since the template 348 is now being held by the imprint lithographytemplate holder 350).

FIG. 38b shows how the substrate handler 356 may, subsequently, be usedto handle a substrate 344, moving the substrate 344 from the storagerack 350 and into the imprint compartment 340 for loading onto thesubstrate stage 352.

FIG. 38c shows that, when loaded on the substrate stage 352, one or moresupports 358, or the substrate stage 352 itself, may be moved to movethe substrate 344 into proximity with the print head 354. Imprintablemedium 360 may then be deposited on the substrate 344 by or via theprint head 354.

FIG. 38d shows that, after imprintable medium 360 has been provided onthe substrate 344, the substrate stage 352 may be moved into approximatealignment with the imprint lithography template holder 350, and/or theimprint lithography template 348 held by the imprint lithographytemplate holder 350. Imprinting of patterns into the imprintable medium360 provided on the substrate 352 may then take place, for example in aknown manner.

FIG. 39 schematically depicts an example of the dummy substrate 346referred to above. The dummy substrate 346 comprises a standardsubstrate 370. In this context, the term ‘standard’ means that thesubstrate 370 can be handled with a conventional, unmodified, substratehandling system. For example, the footprint (e.g. the area and/ordimension(s) and/or general shape) of the substrate 370 will, forexample, match that of a standard wafer or the like that the substratehandling system is primarily designed to handle.

The standard substrate 370 is provided with an arrangement toaccommodate an imprint lithography template 348, thus allowing theimprint lithography template 348 to be handled by appropriate handlingof the standard substrate 370. The arrangement comprises one or moreabutment surfaces 372 that, in use, are located on an upper side of thesubstrate 370, and which substantially extend along one, more, or allsides of the imprint lithography template 348, thus preventingsubstantial movement of the template 348. For instance, the abutmentsurfaces 372 may form a frame or the like that, in use, surrounds theimprint lithography template 348.

One or more biasing elements 374 (e.g. one or more springs or the like)may extend from one or more of the abutment surfaces 372 and into, inuse, contact with the imprint lithography template 348. The biasingelement 374 biases the imprint lithography template 348 into, forexample, contact with another abutment surface 372 or a biasing elementprovided in relation thereto, in order to prevent movement, orsubstantial movement, of the imprint lithography template 348 duringhandling, or storage, or the like. The biasing element 374 is desirablyarranged to come into contact with a base region of the imprintlithography template 348, as opposed to the potentially more delicateand sensitive mesa region 376 on which one or more pattern features areprovided for use in imprinting a pattern into a layer of imprintablemedium.

FIG. 39 shows that, typically, the imprint lithography template 348 willbe loaded on the dummy substrate with the mesa region 376 (on which thepattern features or patterned region will be provided) directed towardsthe dummy substrate 346, or, more specifically, a face of the standardsubstrate 370 constituting a part of that dummy substrate 346. Thisprovides protection for the patterned region provided on the mesa region376, and may also facilitate more straightforward handling of theimprint lithography template 348, and/or subsequent holding of theimprint lithography template 348 by an imprint lithography templateholder.

In the embodiments described herein, the term positioning and/ordeformation of an imprint lithography template arrangement has beendescribed. Positioning, for example, may include holding of the imprintlithography template arrangement. Deformation of, for example, animprint lithography template held by a template holder, could beundertaken directly (e.g. by direct deformation of the template) orindirectly (e.g. by deformation of the holder, which causes deformationof the template).

The position (which includes orientation) and/or deformation (or degreeof deformation) of the imprint lithography template may be genericallyreferred to as a, or the, configuration of the imprint lithographytemplate.

One or more of the features described above in relation to an embodimentof the present invention may additionally or alternatively be used incombination with, or in replacement of, features described in relationto another embodiment as appropriate.

The present invention relates to imprint lithography apparatus suitablefor carrying out or implementing an imprint lithography method orprocess. The imprint lithography apparatus and/or method may be used forthe manufacture of devices, such as electronic devices and integratedcircuits, or the apparatus and/or method may be used for otherapplications, such as the manufacture of integrated optical systems,guidance and detection patterns for magnetic domain memories, flat-paneldisplays, liquid-crystal displays (LCDs), thin film magnetic heads,organic light emitting diodes, etc. An imprint lithography template usedby, or forming a part of the imprint lithography apparatus may comprisepattern features having one or more dimensions of the order ofmicrometers or nanometers.

In this specification, the term “substrate” is meant to include anysurface layers forming part of the substrate, or being provided onanother substrate, such as planarisation layers or anti-reflectioncoating layers.

In use, an imprint lithography template may be held by an imprintlithography template holder. The imprint lithography template holder mayhold the imprint lithography template using one of a number of differentmechanisms, for example using electrostatic and/or magnetic force,mechanical force (e.g. via the use of one or more piezoelectric elementsor the like) and/or by vacuum force. The imprint lithography templatemay be moved by appropriate movement of the imprint lithography templateholder. In use, a substrate may be held by a substrate holder. Thesubstrate holder may hold the substrate using one of a number ofdifferent mechanisms, for example using an electrostatic and/or magneticforce, mechanical force (e.g. a clamp or the like) and/or by vacuumforce. The substrate may be moved by appropriate movement of thesubstrate holder.

In the above embodiments, a single imprint lithography template, asingle imprint lithography template holder, a single substrate holderand a single substrate is provided, and for example in a single chamberor the like. In other embodiments, more than one imprint lithographytemplate, more than one imprint lithography template holder, more thanone substrate holder, and/or more than one substrate may be provided inone or more chambers, for example in order for imprints to be undertakenmore efficiently or quickly (e.g. in parallel). For example, in anembodiment, there is provided an apparatus that includes a plurality(e.g. 2, 3, or 4) of substrate holders. In an embodiment, there isprovided an apparatus that includes a plurality (e.g. 2, 3, or 4) ofimprint lithography template holders and/or templates. In an embodiment,there is provided an apparatus configured to use one imprint lithographytemplate holder and/or one imprint lithography template per substrateholder. In an embodiment, there is provided an apparatus configured touse more than one imprint lithography template holder and/or imprintlithography template per substrate holder. In an embodiment, there isprovided an apparatus that includes a plurality (e.g. 2, 3, or 4) ofimprintable medium dispensers. In an embodiment, there is provided anapparatus configured to use one imprintable medium dispenser persubstrate holder. In an embodiment, there is provided an apparatusconfigured to use one imprintable medium dispenser per imprintlithography template. In an embodiment, where an apparatus is providedthat includes a plurality of substrate holders, the substrate holdersmay share functionalities in the apparatus. For instance, the substrateholders may share a substrate handler, a substrate cassette, a gassupply system (e.g. to create a helium environment during imprinting),an imprintable medium dispenser, and/or a radiation source (for curingthe imprintable medium). In an embodiment, two or more of the substrateholders (e.g. 3 or 4) share one or more functionalities of the apparatus(e.g. 1, 2, 3, 4, or 5 functionalities). In an embodiment, one or morefunctionalities (e.g. 1, 2, 3, 4, or 5) of the apparatus are sharedamong all substrate holders.

The described and illustrated embodiments are to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the scope of theinventions as defined in the claims are desired to be protected. Itshould be understood that while the use of words such as “preferable”,“preferably”, “preferred” or “more preferred” in the description suggestthat a feature so described may be desirable, it may nevertheless not benecessary and embodiments lacking such a feature may be contemplated aswithin the scope of the invention as defined in the appended claims. Inrelation to the claims, it is intended that when words such as “a,”“an,” “at least one,” or “at least one portion” are used to preface afeature there is no intention to limit the claim to only one suchfeature unless specifically stated to the contrary in the claim. Whenthe language “at least a portion” and/or “a portion” is used the itemcan include a portion and/or the entire item unless specifically statedto the contrary.

Further embodiments according to the invention are provided in belownumbered clauses:

1. An imprint lithography apparatus, comprising:

a first frame to be mounted on a floor;

a second frame mounted on the first frame via a kinematic coupling;

an alignment sensor mounted on the second frame, to align an imprintlithography template arrangement with a target portion of a substrate;and

a position sensor to measure a position of the imprint lithographytemplate arrangement and/or a substrate stage relative to the secondframe.

2. The apparatus of clause 1, wherein the first frame is to be mountedon the floor by a vibration isolation system.

3. The apparatus of clause 1 or clause 2, wherein a portion of thesecond frame extends from outside of the first frame, and into a regionlocated within the first frame, so that the measurement of position maybe undertaken relative to or using that portion of the second frame.4. An imprint lithography apparatus, comprising:

a first frame to be mounted on a floor;

a second frame mounted on the first frame via a vibration isolationsystem;

an imprint lithography template arrangement configured, at least in use,to be mounted on the second frame via a kinematic coupling;

an alignment sensor mounted on the second frame, to align the imprintlithography template arrangement with a target portion of a substrate;and

a position sensor to measure a position of a substrate stage relative tothe second frame.

5. The apparatus of clause 4, wherein the second frame is locatedsubstantially within the first frame.

6. The apparatus of clause 4 or clause 5, further comprising a releasecompensation actuator connected between the first frame and the imprintlithography template arrangement.

7. The apparatus of clause 6, wherein a point of connection of therelease compensation actuator is linked to a point of connection of thekinematic coupling via which the imprint lithography templatearrangement is mounted to the second frame.

8. The apparatus of clause 7, wherein the point of connection of therelease compensation actuator is on an opposite side of the imprintlithography template arrangement to the point of connection of thekinematic coupling via which the imprint lithography templatearrangement is mounted to the second frame.9. The apparatus of any of clauses 6 to 8, wherein the releasecompensation actuator extends through the second frame.10. The apparatus of any preceding clause, wherein the substrate stageis a five degree of freedom short stroke substrate stage.11. The apparatus of any preceding clause, wherein the substrate stageis capable of translational long stroke movement along two axes parallelto a plane of the substrate (x and y axes), and along an axisperpendicular to that plane (z axis).12. The apparatus of clause 11, wherein the substrate stage is capableof rotational movement about the two axes that are parallel to the planeof the substrate (rotation about x and y axes).13. The apparatus of clause 11, wherein the substrate stage is capableof rotational movement about the two axes that are parallel to the planeof the substrate (rotation about x and y axes), and about the axis thatis perpendicular to that plane (rotation about z axis), and thesubstrate stage is capable of translational short stroke movement alongthe two axes parallel to the plane of the substrate (x and y axes).14. The apparatus of clause 12, wherein the imprint lithography templatearrangement is capable of translational short stroke movement along thetwo axes parallel to the plane of the substrate (x and y axes), and theimprint lithography template arrangement is capable of rotationalmovement about the axis that is perpendicular to that plane (rotationabout z axis).15. The apparatus of any of clauses 1 to 10, wherein the substrate stageis capable of translational long stroke movement along two axes parallelto a plane of the substrate (x and y axes).16. The apparatus of clause 15, wherein the substrate stage is capableof rotational movement about the two axes that are parallel to the planeof the substrate (rotation about x and y axes).17. The apparatus of clause 15, wherein the substrate stage is capableof rotational movement about the two axes that are parallel to the planeof the substrate (rotation about x and y axes), and about the axis thatis perpendicular to that plane (rotation about z axis), and thesubstrate stage is capable of translational short stroke movement alongthe two axes parallel to the plane of the substrate (x and y axes).18. The apparatus of clause 16 or clause 17, wherein the imprintlithography template arrangement is capable of long stroke movementalong an axis perpendicular to the plane of the substrate (z axis).19. The apparatus of clause 18, when dependent on clause 16, wherein theimprint lithography template arrangement is capable of translationalshort stroke movement along the two axes parallel to the plane of thesubstrate (x and y axes), and the imprint lithography templatearrangement is capable of rotational movement about the axis that isperpendicular to that plane (rotation about z axis).20. The apparatus of any preceding clause, further comprising a heatshield to shield the second frame.21. The apparatus of any preceding clause, wherein the second frame isformed from a material with a low coefficient of thermal expansionand/or a high thermal conductance.22. The apparatus of any preceding clause, further comprising a coolingor thermal conditioning system to cool or thermally condition the secondframe.23. The apparatus of any preceding clause, wherein the second frame isconstructed and/or arranged to have internal dynamical modes that are ofa high frequency.24. The apparatus of any preceding clause, wherein the substrate stageis coupled to the first frame.25. The apparatus of any preceding clause, wherein the substrate stageis, or comprises, or forms a part of one or more selected from thefollowing:

a substrate holder;

a positioner of the substrate;

a positioner of a substrate holder.

26. The apparatus of any preceding clause, wherein the first frame is abase frame, and/or wherein the second frame is a metrology frame.

27. An imprint lithography apparatus, comprising:

a base frame;

a metrology frame;

an imprint lithography template arrangement in connection with the baseframe or the metrology frame via a kinematic coupling and a releasecompensation actuator.

28. The apparatus of clause 27, wherein the kinematic coupling islocated in series with the release compensation actuator.

29. The apparatus of clause 27, wherein a point of connection of therelease compensation actuator is on an opposite side of the imprintlithography template arrangement to a point of connection of thekinematic coupling.

30. An imprint lithography method for using an imprint lithographyapparatus, the apparatus comprising a base frame, a metrology frame, andan imprint lithography template arrangement, the method comprising:

using the imprint lithography arrangement to imprint a pattern into alayer of imprintable medium provided on a substrate, when the imprintlithography arrangement is in connection with the metrology frame;

fixing the pattern provided in the imprintable medium;

moving the imprint lithography template arrangement to disconnect theimprint lithography arrangement from the metrology frame, and connectingthe imprint lithography template arrangement to the base frame; and

releasing the imprint lithography template arrangement from thesubstrate.

31. The method of clause 30, comprising moving the imprint lithographytemplate arrangement by movement of a substrate stage that holds thesubstrate.

32. The method of clause 30 or clause 31, wherein releasing the imprintlithography template arrangement comprises holding the imprintlithography template arrangement using an actuator in connection withthe base frame, and pulling the substrate away from the imprintlithography template arrangement via movement of the substrate stagethat holds the substrate.33. The method of any of clauses 30 to 32, wherein the imprintlithography template arrangement is biased toward connection with themetrology frame, the movement of the imprint lithography templatearrangement overcoming the bias.34. The method of clauses 32 and 33, wherein the actuator is capable ofbiasing the imprint lithography template arrangement toward connectionwith the metrology frame.35. An imprint lithography apparatus, comprising:

a base frame;

a metrology frame connected to the base frame; and

an imprint lithography template arrangement, the imprint lithographytemplate arrangement being movable between a first configuration and asecond configuration, the first configuration defined by the imprintlithography template arrangement being connected to the metrology frame,and the second configuration defined by the imprint lithography templatearrangement being disconnected from the metrology frame and connected tothe base frame.

36. An imprint lithography template arrangement clamping configuration,the clamping configuration including a clamp that comprises:

a base region;

a burl extending from the base region, and arranged in use to come intocontact with the imprint lithography template arrangement, the burl atleast partially flexible in a direction parallel to a plane of theimprint lithography template arrangement, to allow for movement,expansion or compression of the imprint lithography templatearrangement, without slip of the burl relative to the imprintlithography template arrangement;

a space that surrounds the burl;

a seal wall extending from the base region and surrounding the spacethat surrounds the burl, the burl extending further from the base regionthan the seal wall, the seal wall configured to provide, in use, an atleast partial seal with the imprint lithography template arrangement,when the space is at a lower pressure than ambient pressure.

37. The clamping configuration of clause 36, wherein the burl is:

at least 1 mm long;

at least 5 mm long;

at least 5-10 mm long;

at least 10 mm long;

and/or is less than 100 mm long.

38. The clamping configuration of clause 36 or clause 37, wherein theburl extends:

1-10 μm further from the base region than the seal wall; or

3-5 μm further from the base region than the seal wall.

39. The clamping configuration of any of clauses 36 to 38, wherein theclamp comprises a plurality of burls, constructed and arranged to bedistributable around a periphery of the imprint lithography templatearrangement.

40. The clamping configuration of any of clauses 36 to 39, wherein theseal wall comprises:

an outer seal wall that extends around an outer perimeter of a regioncontaining the burl or burls; and

an inner seal wall that extends around an inner perimeter of the regioncontaining the burl or burls.

41. The clamping configuration of any of clauses 36 to 40, comprising aplurality of the clamps, constructed and arranged so as to be disposablearound a periphery of the imprint lithography template arrangement.

42. The clamping configuration of any of clauses 36 to 41, wherein theclamp or clamping configuration is, or forms a part of, another imprintlithography template arrangement.

43. A method of releasing an imprint lithography template from asubstrate that is held on a substrate stage, the method comprising:

pulling the substrate and the imprint lithography template away from oneanother; and

applying a rotation moment to the imprint lithography template, thesubstrate, or both, toward the other, such that at a radial extremity ofan interface between the imprint lithography template and the substrate,there is a cumulative force acting on the substrate that results in thesubstrate being held on the substrate stage.

44. The method of clause 44, wherein a relationship between a pullingforce, or a component thereof, acting through a center of the imprintlithography template, and a moment associated with the rotation isdefined as:F<M/bwhere F is the pulling force, or the component thereof, acting throughthe center of the imprint lithography template, M is the moment inducedby the rotation, and b is a radial distance from the center of theimprint lithography template to the radial extremity of the interfacebetween the imprint lithography template and the substrate.45. The method of clause 43 or clause 44, wherein the method isundertaken at a peripheral region of the substrate.46. An imprint lithography apparatus comprising:

an imprint lithography template holder to hold an imprint lithographytemplate;

a substrate stage to hold a substrate;

wherein, during release of an imprint lithography template from asubstrate, the imprint lithography template holder, the substrate stage,or both, is constructed and arranged to be movable to:

pull the substrate and the imprint lithography template away from oneanother; and

apply a rotation moment to the imprint lithography template, thesubstrate, or both, toward the other, such that at a radial extremity ofan interface between the imprint lithography template and the substrate,there is a cumulative force acting on the substrate that results in thesubstrate being held on the substrate stage.

47. An actuation arrangement to position and/or deform an imprintlithography template arrangement, the arrangement comprising:

a first actuator, locatable, in use, at a first position of the imprintlithography template arrangement;

a second actuator, locatable, in use, at a second, opposite position ofthe imprint lithography template arrangement; and

a signal amplifier to amplify a control signal applicable to both thefirst actuator and the second actuator.

48. The actuation arrangement of clause 47, wherein the first actuatoris locatable directly opposite the second actuator.

49. The actuation arrangement of clause 47 or clause 48, wherein theactuation arrangement comprises:

a plurality of first actuators, locatable, in use, on a first side ofthe imprint lithography template arrangement;

a plurality of second actuators, locatable, in use, on a second,opposite side of the imprint lithography template arrangement; and

a signal amplifier to amplify a control signal applicable to directlyopposing actuators of the pluralities, or to amplify a control signalapplicable to groups of actuators locatable on opposite sides of theimprint lithography template arrangement.

50. The actuation arrangement of any of clauses 47 to 49, wherein eachactuator is a piezoelectric actuator or a Lorentz actuator.

51. The actuation arrangement of any of clauses 47 to 50, wherein theactuation arrangement forms a part an imprint lithography templateholder.

52. An imprint lithography method, comprising:

imprinting an imprint lithography template into a layer of imprintablemedium provided on a substrate to form a pattern in that layer ofimprintable medium;

controlling a position or deformation of the imprint lithographytemplate relative to the substrate when the imprint lithography templateis imprinted into the imprintable medium; and

fixing the pattern provided in the layer of imprintable medium,

wherein controlling the position or deformation of the imprintlithography template relative to the substrate comprises:

undertaking relatively high bandwidth control at a first level when theimprintable medium is in an unfixed, substantially liquid and/orflowable state, then

undertaking higher bandwidth control at a second level, higher than thefirst level, when the imprintable medium is in an intermediate state,in-between the unfixed, substantially liquid and/or flowable state, anda fixed, substantially solid state, and then

undertaking relatively low bandwidth control when the imprintable mediumis in a fixed, substantially solid state.

53. The method of clause 52, wherein controlling a position ordeformation of the imprint lithography template relative to thesubstrate comprises control of a servomechanism.

54. The method of clause 52 or clause 53, wherein controlling a positionof the imprint lithography template relative to the substrate when theimprint lithography template is imprinted into the imprintable mediumcomprises aligning, or maintaining alignment of, the imprint lithographytemplate arrangement relative to a target portion the substrate.55. An actuation arrangement to position and/or deform an imprintlithography template arrangement, the arrangement comprising:

an actuator, locatable, in use, around the imprint lithography templatearrangement;

fixed abutment points to fix three degrees of freedom of the imprintlithography template arrangement, the three degrees of freedom beingtranslation along a first axis parallel to a plane of the imprintlithography template arrangement, translation along a second axis,perpendicular to the first axis and parallel to the plane of the imprintlithography template arrangement, and rotation about a third axis,perpendicular to the first and second axes; and

a controller to control a force provided by the actuator to the imprintlithography template arrangement, the controller configured to ensurethat the provided force is such that a cumulative force acting along thefirst axis, second axis, and about the third axis, is minimal.

56. The actuation arrangement of clause 55, further comprising a biasingmember, arranged to bias, in use, the imprint lithography templatearrangement into contact with the fixed abutment points.

57. The actuation arrangement of clause 55 or clause 56, wherein thecumulative force is minimal in that that a force applied to one, more orall fixed abutment points, is:

less than 5% of a total force applied to the imprint lithographytemplate arrangement; or

less than 4% of a total force applied to the imprint lithographytemplate arrangement; or

less than 3% of a total force applied to the imprint lithographytemplate arrangement; or

less than 2% of a total force applied to the imprint lithographytemplate arrangement; or

less than 1% of a total force applied to the imprint lithographytemplate arrangement; or

substantially 1% of a total force applied to the imprint lithographytemplate arrangement; or

substantially 0% of a total force applied to the imprint lithographytemplate arrangement.

58. The actuation arrangement of any of clauses 55 to 57, wherein theimprint lithography template arrangement is substantially rectangular,and wherein the actuation arrangement comprises three fixed abutmentpoints arranged such that:

two fixed abutment points are locatable along one side of the imprintlithography template arrangement; and

one fixed abutment point is locatable along an adjacent side of theimprint lithography template arrangement.

59. The actuation arrangement of any of clauses 55 to 58, wherein thecontroller is configured to ensure that the provided force is such thatthe cumulative force acting along the first axis, second axis, and aboutthe third axis, is minimal during a deformation control mode.60. The actuation arrangement of any of clauses 55 to 59, wherein theactuation arrangement forms a part of an imprint lithography templateholder.61. A method of controlling a position and/or deformation of an imprintlithography template arrangement, the method comprising

fixing three degrees of freedom of the imprint lithography templatearrangement, the three degrees of freedom being translation along afirst axis parallel to a plane of the imprint lithography templatearrangement, translation along a second axis, perpendicular to the firstaxis and parallel to the plane of the imprint lithography templatearrangement, and rotation about a third axis, perpendicular to the firstand second axes; and

controlling a force provided to the imprint lithography templatearrangement to control a position or deformation of the imprintlithography template arrangement, ensuring that the provided force issuch that a cumulative force acting along the first axis, second axis,and about the third axis, is minimal.

62. An imprint lithography apparatus, comprising:

an imprint lithography template arrangement for use in imprinting apattern into a layer of imprintable medium provided on a substrate;

an actuator to position and/or deform the imprint lithography templatearrangement;

a substrate stage to hold the substrate;

an alignment sensor to align the imprint lithography templatearrangement relative to a target portion of the substrate, the alignmentsensor having a first detection bandwidth;

a relative position sensor to measure a relative position between theimprint lithography template arrangement and the substrate, the relativeposition sensor having a second detection bandwidth greater than thefirst detection bandwidth of the alignment sensor.

63. The apparatus of clause 62, wherein the alignment sensor has adetection bandwidth of:

less than 10 Hz; or

less than 5 Hz.

64. The apparatus of clause 62 or clause 63, wherein the relativeposition sensor has a detection bandwidth of:

greater than 100 Hz; or

greater than 200 Hz.

65. The apparatus of any of clauses 62 to 64, wherein the actuatorcomprises, or is in connection with, a force sensor to measure, directlyor indirectly, a force applied by the actuator.

66. The apparatus of clause 65, wherein the force sensor has a thirddetection bandwidth, that third detection bandwidth being greater thanthe first detection bandwidth of the alignment sensor.

67. The apparatus of clause 65 or clause 66, wherein the force sensor isa position or current sensor.

68. An imprint lithography method, comprising:

controlling a position and deformation of the imprint lithographytemplate relative to the substrate to achieve a position and deformationsubstantially as intended; and

when the imprint lithography template is positioned and deformedsubstantially as intended, reducing a control bandwidth related to thedeformation of the imprint lithography template.

69. The method of clause 68, wherein the control bandwidth is animplementation bandwidth related to the implementation of thedeformation of the imprint lithography template.

70. The method of clause 68 or clause 69, wherein the bandwidth isreduced to:

less than 100 Hz;

less than 50 Hz;

less than 10 Hz;

less than 5 Hz;

a few Hertz; and/or

a bandwidth that is in the detection bandwidth of an alignment sensorused in the alignment of the imprint lithography template arrangementwith a target portion of the substrate.

71. The method of any of clauses 68 to 70, further comprising imprintingthe imprint lithography template into a layer of imprintable mediumprovided on a substrate to form a pattern in that layer of imprintablemedium, and wherein the controlling of the position and the deformationis undertaken:

before the imprinting; or

during the imprinting, and before the pattern is fixed into asubstantially solid state; or

before and during the imprinting, and before the pattern is fixed into asubstantially solid state.

72. An imprint lithography apparatus, comprising:

an imprint lithography template arrangement for use in imprinting apattern into a layer of imprintable medium provided on a substrate;

an actuator to position and/or deform the imprint lithography templatearrangement, the actuator comprising, or is in connection with, a forcesensor to measure, directly or indirectly, a force applied by theactuator, the force sensor having a first detection bandwidth;

a substrate stage to hold the substrate;

an alignment sensor to align the imprint lithography templatearrangement relative to a target portion of the substrate, the alignmentsensor having a second detection bandwidth, wherein the first detectionbandwidth is greater than the second detection bandwidth.

73. The apparatus of clause 72, further comprising a control arrangementconfigured to receive an output from the force sensor, and configured toconvert the output into a position of the imprint lithography templatearrangement.

74. The apparatus of clause 72 or clause 73, wherein second detectionbandwidth is:

less than 10 Hz; or

less than 5 Hz.

75. The apparatus of any of clauses 72 to 74, wherein the firstdetection bandwidth is:

greater than 50 Hz; or

greater than 100 Hz; or

greater than 200 Hz.

76. The apparatus of any of clauses 72 to 75, wherein each of aplurality of actuators comprises, or is in connection with, a forcesensor.

77. The apparatus of any of clauses 72 to 76, wherein the or each forcesensor is a position or current sensor.

78. A method of aligning an imprint lithography template arrangementrelative to a target portion of a substrate, the method comprising:

using an alignment sensor to align the imprint lithography templatearrangement relative to a target portion of the substrate, the alignmentsensor having a first detection bandwidth;

using a force sensor, constituting a part of, or being in connectionwith an actuator, to determine a force applied to the imprintlithography template arrangement by the actuator, the force sensorhaving a second detection bandwidth, that second detection bandwidthbeing greater than the first detection bandwidth of the alignmentsensor; and

determining a position, or change in position, of the imprintlithography template arrangement from the determination of the force,and using that position, or change in position, in the alignment of theimprint lithography template arrangement.

79. An imprint lithography apparatus, comprising:

an imprint lithography template arrangement for use in imprinting apattern into a layer of imprintable medium provided on a substrate;

a substrate stage to hold the substrate; and

a gas dispensation arrangement to provide a gaseous atmosphere in whichthe imprinting of the pattern is to take place, the gas dispensationarrangement configured to dispense gas in an asymmetric manner in theprovision of the gaseous atmosphere.

80. The apparatus of clause 79, wherein the gas dispensation arrangementis configured to dispense gas in an asymmetric manner in or into aregion located in-between the imprint lithography template arrangementand the substrate holder and/or substrate.

81. The apparatus of clause 79 or clause 80, wherein the gasdispensation arrangement comprises a plurality of outlets that areasymmetrically distributed, or asymmetrically distributable, around theimprint lithography template arrangement.

82. The apparatus of any of clauses 79 to 81, wherein the gasdispensation arrangement comprises a plurality of outlets distributed,or distributable, around the imprint lithography template arrangement,the gas dispensation arrangement configured to dispense gas at differentpressures at different outlets, to thus dispense gas in an asymmetricmanner in the provision of the gaseous atmosphere.83. The apparatus of any of clauses 79 to 82, wherein the gasdispensation arrangement comprises a plurality of outlets distributed,or distributable, around the imprint lithography template arrangement,the gas dispensation arrangement configured to dispense gas at differenttimes at different outlets, to thus dispense gas in an asymmetric mannerin the provision of the gaseous atmosphere.84. The apparatus of any of clauses 79 to 83, wherein the gasdispensation arrangement is configured to dispense helium.85. An imprint lithography method, comprising:

providing a gaseous atmosphere in which imprinting of a pattern into alayer of imprintable medium provided on a substrate is to take place;

wherein the gas constituting the gaseous atmosphere is dispensed in anasymmetric manner.

86. An imprint lithography apparatus, comprising:

an imprint lithography template arrangement for use in imprinting apattern into a layer of imprintable medium provided on a substrate, theimprint lithography template arrangement comprising, at least in use, animprint lithography template provided with a patterned region to providethe pattern;

a substrate stage to hold the substrate; and

a contamination barrier dividing the apparatus into at least tworegions:

i) a first, relatively unclean, region in which is located a movableelement; and

ii) a second, relatively clean, region in which is located the substratestage and, if holding a substrate, the substrate itself, and thepatterned region of the imprint lithography template.

87. The apparatus of clause 86, wherein the first region is a generallyupper region of the apparatus, and the second region is a generallylower region of the apparatus.

88. The apparatus of clause 86 or clause 87, wherein at least a portionof a reverse side of the imprint lithography template, opposite to theside on which the patterned region is provided, is located or locatablein the second region.

89. The apparatus of clause 88, wherein in the vicinity of the at leasta portion of the reverse side of the imprint lithography template, thecontamination barrier is formed from a material substantiallytransparent to actinic radiation.

90. The apparatus of any of clauses 86 to 89, wherein the contaminationbarrier comprises a tray or container, located between fixed parts ofthe imprint lithography apparatus, to catch contamination.

91. The apparatus of any of clauses 86 to 90, wherein the contaminationbarrier in comprises a flexible member located between movable parts ofthe imprint lithography apparatus, and/or between a fixed part and amovable part of the imprint lithography apparatus.92. The apparatus of any of clauses 86 to 91, wherein at least a portionof the contamination barrier substantially surrounds the imprintlithography template arrangement.93. The apparatus of any of clauses 86 to 92, wherein the contaminationbarrier extends generally across the imprint lithography apparatus.94. The apparatus of any of clauses 86 to 93, wherein the movableelement is configured for use in conjunction with the imprintlithography template in providing a pattern in the layer of imprintablemedium.95. The apparatus of any of clauses 86 to 94, wherein the movableelement comprises one or more selected from, or an actuator for one ormore selected from, the following:

a part of the imprint lithography template arrangement, such as animprint lithography template holder and/or an imprint lithographytemplate positioner;

an imprint lithography template holder;

an imprint lithography template positioner;

a camera;

a sensor; and/or

a radiation source.

96. An imprint lithography apparatus, comprising:

an imprint compartment, in which is located an imprint lithographytemplate arrangement for use in imprinting a pattern into a layer ofimprintable medium provided on a substrate, and a substrate stage tohold the substrate; and

a print head compartment in connection with the imprint compartment viaa sealed or sealable access port, the print head compartment comprisingan actuator to move a print head from the imprint compartment into theprint head compartment, and/or to move a print head into the imprintcompartment from the print head compartment.

97. The apparatus of clause 96, wherein the actuator is arranged to movean arm, the arm arranged to hold the print head.

98. The apparatus of clause 97, wherein the actuator is located belowthe arm.

99. The apparatus of clause 97 or clause 98, wherein the arm is fullylocatable within the print head compartment.

100. The apparatus of any of clauses 96 to 99, wherein the print headcompartment comprises a gas shower located adjacent to the access port.

101. The apparatus of any of clauses 96 to 100, wherein the print headcompartment comprises a further, sealable, access port to provide accessto a print head located or locatable in the print head compartment.

102. The apparatus of any of clauses 96 to 102, wherein, at least inuse, the imprint compartment is maintained at a higher gas pressure thana gas pressure within the print head compartment.

103. An imprint lithography apparatus, comprising:

a substrate handling system to hold and/or move a substrate, onto whicha layer of imprintable medium is to be provided;

wherein the substrate handling system is configured to also function asan imprint lithography template handling system.

104. The apparatus of clause 103, wherein the substrate handling systemcomprises: a substrate handler to load a substrate onto a substratestage; and/or a substrate stage.

105. The apparatus of clause 103 or clause 104, wherein the substratehandling system in use, handles a dummy substrate, the dummy substratecomprising a standard substrate and, in connection with the standardsubstrate, an arrangement to accommodate an imprint lithographytemplate, the arrangement located, in use, on an upper side of thestandard substrate.106. A dummy substrate for use in handling an imprint lithographytemplate, the dummy substrate having a standard substrate and, inconnection with the standard substrate, an arrangement to accommodate animprint lithography template, the arrangement being located, in use, onan upper side of the standard substrate.107. The dummy substrate of clause 106, wherein the arrangement toaccommodate an imprint lithography template comprises an abutmentsurface, and a biasing element to bias the imprint lithography templateinto contact with the abutment surface.108. The dummy substrate of clause 107, wherein the abutment surfaceand/or the biasing element is/are arranged to contact a base region ofthe imprint lithography template.109. An imprint lithography method, comprising:

in an imprint lithography apparatus, using a substrate handling systemto handle, directly or indirectly, an imprint lithography template.

110. The method of clause 109, wherein the substrate handling systemhandles the imprint lithography template by handling a dummy substratethat is configured to accommodate the imprint lithography template.

111. The method of clause 110, wherein the imprint lithography templateis loaded on the dummy substrate with a patterned region of the imprintlithography template directed towards the dummy substrate.

The invention claimed is:
 1. An actuation arrangement to position and/or deform an imprint lithography template arrangement, the actuation arrangement comprising: a first actuator located, in a use, at a first position of the imprint lithography template arrangement; a second actuator located, in a use, at a second, opposite position of the imprint lithography template arrangement; a signal amplifier to amplify a control signal applicable to both the first actuator and the second actuator; abutment points to fix at least three degrees of freedom of the imprint lithography template arrangement; and a control system to control a force provided by the first and/or second actuator, the control system configured to ensure that the provided force is such that the force applied to or through one or more of the abutment points is less than 5% of the total force applied.
 2. The actuation arrangement of claim 1, wherein the first actuator is located, in a use, directly opposite the second actuator.
 3. The actuation arrangement of claim 1, comprising: a plurality of first actuators located, in a use, on a first side of the imprint lithography template arrangement; a plurality of second actuators located, in a use, on a second, opposite side of the imprint lithography template arrangement; and a signal amplifier to amplify a control signal applicable to directly opposing actuators of the pluralities, or to amplify a control signal applicable to groups of actuators locatable on opposite sides of the imprint lithography template arrangement.
 4. The actuation arrangement of claim 1, wherein each actuator is a piezoelectric actuator or a Lorentz actuator.
 5. The actuation arrangement of claim 1, wherein first and second actuators of the actuation arrangement form a part of an imprint lithography template holder.
 6. The actuation arrangement of claim 1, wherein the control system is configured to produce the control signal, the control signal configured to cause the first and/or second actuator to apply a compressive force to the imprint lithography template arrangement.
 7. An imprint lithography apparatus, comprising: an imprint lithography template arrangement for use in imprinting a pattern into a layer of imprintable medium provided on a substrate; abutment points to fix at least three degrees of freedom of the imprint lithography template arrangement; an actuation arrangement to position and/or deform the imprint lithography template arrangement, the actuation arrangement comprising: a first actuator located, in a use, at a first position of the imprint lithography template arrangement, a second actuator located in a use, at a second, opposite position of the imprint lithography template arrangement, and a signal amplifier to amplify a control signal applicable to both the first actuator and the second actuator, and a control system to control a force provided by the first and/or second actuator, the control system configured to ensure that the provided force is such that the force applied to or through one or more of the abutment points is less than 5% of the total force applied; and a substrate stage to hold the substrate.
 8. The imprint lithography apparatus of claim 7, further comprising a control system configured to produce the control signal, the control signal configured to cause the first and/or second actuator to apply a compressive force to the imprint lithography template arrangement.
 9. The imprint lithography apparatus of claim 7, wherein the first actuator is located, in a use, directly opposite the second actuator.
 10. An imprint lithography method, comprising: fixing at least three degrees of freedom of an imprint lithography template arrangement using abutment points; positioning and/or deforming the imprint lithography template arrangement based on a control signal and using a first actuator located at a first position of the imprint lithography template arrangement and a second actuator located at a second, opposite position of the imprint lithography template arrangement, wherein a signal amplifier amplified the control signal applicable to both the first actuator and the second actuator and wherein a force provided by the first and/or second actuator is controlled to ensure that the provided force is such that the force applied to or through one or more of the abutment points is less than 5% of the total force applied; and imprinting at least part of the imprint lithography template arrangement into a layer of imprintable medium provided on a substrate to form a pattern in that layer of imprintable medium.
 11. The method of claim 10, wherein the first actuator is located directly opposite the second actuator.
 12. The method of claim 10, wherein the positioning and/or deforming uses a plurality of first actuators located on a first side of the imprint lithography template arrangement and a plurality of second actuators located on a second, opposite side of the imprint lithography template arrangement; and comprising amplifying a control signal applicable to directly opposing actuators of the pluralities, or a control signal applicable to groups of actuators locatable on opposite sides of the imprint lithography template arrangement.
 13. The method of claim 10, wherein each actuator is a piezoelectric actuator or a Lorentz actuator.
 14. The method of claim 10, wherein the control signal causes the first and/or second actuator to apply a compressive force to the imprint lithography template arrangement.
 15. An actuation arrangement to position and/or deform an imprint lithography template arrangement, the actuation arrangement comprising: a first actuator located, in a use, at a first position of the imprint lithography template arrangement; a second actuator located, in a use, at a second, opposite position of the imprint lithography template arrangement; a force sensor of, or connected with, the first and/or second actuator, the force sensor configured to measure, directly or indirectly, a force applied by the respective first and/or second actuator, the force sensor having a first detection bandwidth greater than a second detection bandwidth of an alignment sensor to align the imprint lithography template arrangement relative to a target portion of a substrate for imprinting thereon of a pattern by the imprint lithography template arrangement; and a signal amplifier to process the control signals for the first actuator and the second actuator in a manner such that each of the control signals experiences a substantially same noise introduced by the amplifier.
 16. The actuation arrangement of claim 15, further comprising a control system configured to generate a control signal for the amplifier to cause the first and/or second actuator to apply a compressive force to the imprint lithography template arrangement.
 17. The actuation arrangement of claim 15, wherein the actuation arrangement comprises: a plurality of first actuators located, in a use, on a first side of the imprint lithography template arrangement; a plurality of second actuators located, in a use, on a second, opposite side of the imprint lithography template arrangement; and a signal amplifier to amplify one or more control signals applicable to directly opposing actuators of the pluralities, or to amplify one or more control signals applicable to groups of actuators locatable on opposite sides of the imprint lithography template arrangement.
 18. The actuation arrangement of claim 15, wherein each actuator is a piezoelectric actuator or a Lorentz actuator.
 19. The actuation arrangement of claim 15, wherein first and second actuators of the actuation arrangement form a part of an imprint lithography template holder.
 20. The actuation arrangement of claim 15, further comprising: the imprint lithography template arrangement, the imprint lithography template arrangement for use in imprinting a pattern into a layer of imprintable medium provided on a substrate; and a substrate stage to hold the substrate. 